Kudzu bugs on caneberries?

Kudzu bugs (Megacoptera criberia) on raspberry plants at the Piedmont Research Station, Salisbury, NC. Photo: PRS.

My Monday morning  began with two phone calls about the same thing: kudzu bugs on caneberries.  Both calls came from western North Carolina, but kudzu bugs are widespread throughout the southeast.  See here for a map of kudzu bug distribution from the Megacoptera Working Group.  Kudzu bugs (Megacoptera criberia) are yet another invasive species from eastern Asia that has been detected in the southeastern US in recent years.  Kudzu bugs appear to specialize on legumes, including cultivated beans and kudzu, and can cause cause economic damage to soybeans.  My NC State Entomology colleague, Dominic Reisig, has published extensive information on kudzu bug at his blog.  Interestingly, both caneberry sites that prompted my morning calls were also near soybeans.

Raspberry plants at the Piedmont Research Station, Salisbury, NC. Photo: PRS.

Kudzu bugs are also nuisance pests.  Like multicolored Asian ladybeetles and brown marmorated stink bugs, they congregate in structures to overwinter.  Also like these other two home invading invasives, kudzu bugs release stinky defensive chemicals when disturbed.  Migration to overwintering sites is likely happening right now, and this may be at least part of the reason we are currently seeing them on caneberries.  Primocanes may be attractive because they are relatively young when compared other surrounding vegetation.

Kudzu bug aggregation on a home. Photo: Danial Suiter, University of Georgia, via Bugwood Network.

It's unclear if kudzu bugs will feed on blackberries and raspberries.  Kudzu bugs have piercing mouthparts, so damage is often not visible right away.  Following kudzu bug feeding in soybeans, lesions appear on stems (their preferred feeding site).  Despite the fact that adult kudzu bugs can be present in soybeans in very high numbers, they do not appear to cause economic damage in that crop unless they are reproducing and nymphs are present.  Nymphs look markedly different than adult kudzu bugs.  They are smaller and fuzzy (see below). The treatment threshold in soybeans is 15 nymphs per 15 sweeps.  Soybean plants are extremely good at compensating for damage throughout their growing season, which likely contributes to this relatively high threshold.

Kudzu bug feeding lesions on soybean stem. Photo: Dominic Reisig, NC State Entomology

 

Late season kudzu bug damage on soybeans at the Sandhills Research Station. Photo: Jeremy Martin, Superintendent.

Kudzu bug nymphs on soybean. Reproductively active kudzy populations (where nymphs are present) can cause damage in soybeans.

If kudzu bugs are observed on caneberries, scout stems for lesions and nymphs.  If either are present, this would represent a new host for this insect, and that information should be communicated to me and your extension agent.  If kudzu bugs are not feeding on caneberries, they may just be stopping en route to their overwintering sites (structures, leaf litter, and other sheltered areas). This past spring, kudzu bugs were observed aggregated on several non host plants after exiting their overwintering sites.

SWD detections increase

Spotted wing drosophila (SWD) detections in the upper Midwest continue to increase.  SWD adults and larval damage is now confirmed from :
Illinois
Iowa
Minnesota 
Wisconsin

I'll have a detailed update on our SWD research, extension, and education efforts next week.

Welcome, Bill Cline!

Bill Cline describing Blueberry Stunt, Red Ringspot Virus, & Stem Blight the 2011 Blueberry Field Day. Photo: HJB

As you may have noticed below, NC State Plant Pathologist and overall blueberry expert, Bill Cline has joined the blog and will be posting updates on blueberry insects.  Bill is much closer to the heart of North Carolina blueberry production than I am, so I am excited that he will be able to share insect sightings as they happen.

Flea beetle damage on blueberries

Flea beetle damage has been observed on unsprayed blueberry plots at the NCSU Horticultural Crops Research Station in Castle Hayne.  Feeding is mostly on new succulent shoots that have emerged following post-harvest summer pruning (hedging), so these are next year's bearing shoots that need to retain their leaves in order to set flower buds for the 2013 crop. Much of the damage is cosmetic, but where shoots are completely defoliated, or the shoots themselves are eaten, yield will be reduced in 2013.

 Flea beetles are rarely a problem on blueberry in North Carolina, but are more widely observed (and reported) on blueberry in Florida and Georgia.

Another reason to appreciate bees & wasps in grapes

At last Friday's vineyard tour, one of the most common insect questions I get from grape growers again came up. "What can I do about wasps and (less commonly) bees in my grapes?"

My feelings are clear on this subject. I think there is little to be gained from using insecticides against these mostly beneficial insects and significant harm that could be done, both through extending your harvest window and by harming predators and pollinators.  You can read my thoughts on this subject and what growers can do instead of spraying, here.

Today, I read about an even better reason to appreciate wasps, in particular, in your vineyard.  NPR's The Salt blog highlights research from Italy that demonstrates that wasps move wine-fermenting yeasts throughout vineyards and have likely contributed to the evolution of these important yeasts.  You can find the full article here.

More information
What to watch for - Bees and wasps in grapes
Thank the simple wasp for that complex glass of wine - The Salt
Role of social wasps in Sacromyces cerevisiae ecology and evolution - Proceedings of the National Academy of Sciences

Spotted wing drosophila detected in Arkansas

On July 9th, Donn Johnson at his team at the University of Arkansas detected the first spotted wing drosophila adults in Arkansas.  You can read about this find here and see the trap capture data at the SWD*VMN.

Spotted wing drosophila biology and management in North Carolina strawberries

The third in my summer series of spotted wing drosophila (SWD) factsheets focuses on strawberries.  Please note, factsheets are shared via Google Documents, which is great for quickly and easily posting files but does sacrifice image quality.  If you would like a printer quality digital copy of this factsheet. Please email me.


You can find the first factsheet on SWD biology and management in North Carolina caneberries here and the second on post harvest SWD significance and sampling here.



This Thursday I will be attending a strawberry field day in Watauga County, NC at a farm that grows day neutral (summer fruiting) strawberries and sharing information from this factsheet as well as results from our spring strawberry SWD management experiments at the Central Crops Research Station. Day neutral strawberries present unique SWD management challenges because they fruit through fall, when the highest SWD populations of the year occur.  You can read more about day neutral strawberries at the North Carolina Strawberry Association's blog.

More information
Strawberry field day - Watauga County Cooperative Extension

NC State summer vineyard tour - 27 July

NC State University grape experts will be leading a tour of muscadine and vinfera vinyards on 27 July. We'll be hosted by Cauble Creek Vineyard and Morgan Ridge Vineyard, both in Rowan County.

 I will be discussing the Grape Root Borer Volunteer Monitoring Network (GRB*VMN) and kicking off 2012 monitoring!

 Preregistration is required by 24 July. See the program below for the registration form and details on the other presenters.

North Carolina hops arthropod summary

Developing hops cones at the Lake Wheeler Road Field Lab, Raleigh, NC. Photo; HJB

In preparation for the upcoming NC State Hops Field Tour next week, I have been crunching some data from our hops observations from last year at the Lake Wheeler Road Field Lab hop yard.  The results so far have been very interesting.

Background
Our goal, as part of the larger NC State Hops Project, was to learn what arthropods (insects and mites) were present in North Carolina grown hops and which of these insects may become pests in commerical production.We knew from work in the Pacific Northwest that twospotted spider mite and hop aphid were potentially significant pests of hops that occur in North Carolina, but we didn't know what other insects pests may be present.  We utilized the research hop yard at the Lake Wheeler Road Field Lab, which included 10 different hops varieties planted in four, five plant plots, to conduct our observations.  We sampled insects and mites in two ways: 1. We collected 10 leaf samples from each plot weekly and counted the number of spider mites, predatory mites (good guys), aphids, and leafhopper nymphs, and 2. We placed a yellow sticky trap in each plot, which was changed weekly.  We then counted the number adult leafhoppers, thrips, aphids, and beneficial insects (in this case, ladybugs) on each trap.

In addition to leaf samples and trapping, we rated defoliation on plants due to caterpillar or beetle (most commonly Japanese beetle) feeding.  We visually divided the three middle plants in each plot into thirds and rated percent defoliation on the upper, middle, and lower third of each plant.  While both caterpillars and Japanese beetles were present throughout the growing season, overall defoliation was minor (less than 1% each week) and localized on the top third of plants.

One plot at the Lake Wheeler Road Field Lab, early 2011. Photo: HJB

Results
While we observed spider mites and aphids in our samples, as expected, we also observed two other groups of insects that we did not anticipate, thrips and leafhoppers, because they are not considered pests in the Pacific Northwest. 

Looking first at our leaf observations, we found differences in spider mite densities throughout the season between varieties.  We express the number of mites multiplied by the days between observations and totaled over the season as "mite days" to compare infestation over time. Click on the images below to enlarge them.

Cumulative spider mite days in hops varieties during the 2011 growing season. Centennial had far few mites than other varieties observed, with Zeus also trending lower.

While Centennial had fewer mites than other varieties, more aphids and leafhopper nymphs were present on leaf samples.  This is a very interesting difference, because foliar feeding aphids may not necessarily be problematic in hops (presence in harvested cones is the real concern) and we do not know whether leafhoppers are a pest in eastern hops or just commonly present.

Aphid and leafhoppers nymphs per leaf in foliage samples during 2011. Note that Centennial has by far the greatest numbers of either aphids or leafhopper nymphs.

While spider mites were present pretty much continuously throughout the growing season, leafhopper nymphs appeared only for a few sampling dates across all plots.  The presence of leafhopper nymphs suggests that they are reproducing on hops, which also does not seem to occur in the Pacific Northwest. Predatory mites were present in on some dates but in very low numbers, and aphid numbers were generally low across the board.

Spider mites, mite eggs, leafhopper nymphs, and aphids in leaf samples across all varieties.

The most frequently captured leafhopper species in traps was the versute leafhopper, Graphocephala versuta, a distinctive species common throughout the eastern US.  We do not know if the leafhopper nymphs present on leaves are also this species.

Graphocephala versulta. Photo via BugGuide, © Troy Bartlett

The most common insects captured overall on our yellow sticky traps were thrips.  Thrips on sticky traps cannot be identified to species, and yellow is attractive to pest and non pest thrips alike, so we cannot say if the thrips we captured were potential pests.  However, thrips were not commonly observed on leaf samples, and typical "silver-leafing" thrips damage was not observed on leaves.  Aphids were also captured on traps but were less common on leaf samples.

Insect captures in yellow sticky traps throughout the growing season, 2011.  Thrips numbers should be multiplied by ten to get the actual number observed per trap.

This first year of observations is intriguing, and I am excited to share them in greater detail next weekend!  I am also excited to compare these results to data from from other components of the NC State Hops Project, including fertility and yield (posted here).  Cascade* and Zeus were the highest yielding plants in 2011 and Zeus had low mite numbers.  Mites are attracted to and reproduce more on stressed plants, and I suspect that yield relationship is more due to the fact that these varieties were vigorously growing and generally happier in NC than the others, therefore hosting less mites.

It's very important to note that these insect observations are only from one field season, so while they are interesting, they don't necessarily tell us what to expect in the long term.  It's also important to understand that presence does not necessarily mean pest.  While we observed large numbers of thrips in yellow sticky traps, we did not necessarily see large numbers on foliage nor did we see any evidence damage, and while leafhoppers are common in and around NC hops, we do not know they are causing significant damage.

Update, 14 July
For those of you unable to attend today's field tour, you can view the slides from my presentation here.

Update, 31 July
As the commenter below pointed out, Centennial was a poor producer, while Zeus had relatively high yields.  Cascade, the other relatively strong yielding variety, had mid-range mite populations and low populations of other leaf feeding pests.

More information

Two Opportunities to Visit the NC State Research Hop Yards - NC Alternative Crops and Organics

NC State Hops Project
All hops posts - NC Small Fruit & Specialty Crop IPM

Spotted wing drosophila in the city

Spotted wing drosophila mating pair outside a Wake County, NC home.  Photo: Matt Bertone.

Entomologists at the North Carolina Nature Research Center and NC State University are partnering to count the creepy crawlers and unseen critters that live inside our houses, and have found spotted wing drosophila (SWD) during their search.

Led by Michelle Trautwein, Assistant Director of the Biodiversity Laboratory at the Nature Research Center, Arthopods of Our Homes seeks to understand the diversity of insects and other arthropods in homes and how human residents influence their populations.  In the handful of houses the team has sampled so far, they have found over 100 species.  Not necessarily a surprise to us entomologists, who know insects are all around us, but it is exciting to demonstrate such diversity so close to home!

Eagle eyed dipterist Matt Bertone, part of the Arthropods of Your Home team, spotted two mating SWD in the yard of a recently sampled home and collected a few others inside.  The flies inside are particularly interesting, as we suspect that man made structures may help adult flies overwinter because they don't diapause, or hibernate, like many other insects.  Understanding how common SWD is in non agricultural habitats and during what times of year we can find them will help us develop whole-system management tools, not to mention help us understand how significant a concern they may before your backyard garden.

Matt will be record SWD finds as part of the SWD*VMN (Spotted Wing Drosophila Volunteer Monitoring Network).  You can find the record for the first one here.

More information

On location with the Arthropods of Our Homes team - Your Wild Life Blog 

Sign up for Arthropods of Our Homes - Your Wild Life

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Spotted wing drosophila post harvest and larval sampling factsheet

I've completed the second in a series of spotted wing drosophila (SWD) factsheets.  This one addresses post harvest concerns about SWD and summarizes larval sampling methods.  As with much relating to SWD, there is a lot we don't yet know, but this factsheet provides a starting point for those interested in developing a sampling plan for larval SWD.



Please note, factsheets are shared via Google Documents, which is great for quickly and easily posting files but does sacrifice image quality.  If you would like a printer quality digital copy of this factsheet. Please email me.

You can find the first factsheet on SWD biology and management in North Carolina caneberries here.

The 2012 "Dirty Dozen" and "Clean 15" lists

The Environmental Working Group's annual Dirty Dozen and Clean 15 lists have been released, and once again, several fruits are included. Strawberries, grapes, and blueberries are all on the Dirty Dozen list, which measure ranks produce by pesticide residue levels.  Last year, I wrote about what lists like the Dirty Dozen mean for IPM practitioners and researchers.  You can find that post here.

Do it yourself: take insect photos and collect samples for diganosis

I receive lots of emails from extension agents, growers, and homeowners requesting insect identification.  Oftentimes, these emails are accompanied by photographs of the insect, associated damage, or both.  Sometimes, these images are useful in determining what species, or more commonly, what general group of insects are responsible for the damage.  Most of the time, however, these images do not aid in insect identification and can even make it more difficult.

A group of entomologists from throughout the southeastern US have developed a series of training modules on basic insect identification, including Wiki pages, targeted to master gardeners, homeowners, and invasive species first detectors.  The First Detector Wiki describes how to identify some of the most common pest species as well as some of the most important invasive species spreading throughout the US.

More importantly for the budding entomological photographer, there are pages which cover the basis of how to properly photograph and submit images for digital diagnosis and how to collect and preserve insect samples for diagnosis.

The First Detector Wiki also includes information about some of the many pests in several insects orders.  Each of these order-level pages also includes information on how to take a good picture of members of that group.  For example, information to on taking a diagnostic photo of Dipterans (flies) is here.  The Diptera and Coleoptera (beetle) pages were developed by recent NC State Entomology graduate Matt Bertone in collaboration with myself and Mark Abney.

If you are interested in photographing insects for reasons beyond simple diagnosis, there are lots of amazing sites devoted to insect photography.  Some of my favorites are from Alex Wild (here and here) and Piotr Naskrecki (here).

More information
How to properly photograph and submit images for digital diagnosis - First Detector Wiki
Collecting insects - First Detector Wiki

SWD factsheets for Summer 2012

I have started working on a series of updated spotted wing drosophila (SWD) factheets for Summer 2012, the first of which is a general factsheet for caneberry (blackberry and raspberry) growers.
Look for more updated factsheets for strawberries, blueberries, grapes, homeowners, and on trapping and larval sampling soon.

Spotted wing drosophila fact sheets from Penn State

The IPM team at Penn State University has put together several nice fact sheets on spotted wing drosophila (SWD) in the last several months.  I particularly like the images of non SWD males in this fact sheet and the character summaries illustrated here.  I've used these images to illustrated SWD characters to participants in the SWD*VMN and extension agents monitoring for SWD.

More information
Spotted wing drosophila pest alert - Penn State University Extension

Reminder: blackberry field tour this Thursday!

Green June beetle on ripe blackberries at the Lower Coastal Plain Research Station, Kinston, NC during a research trial in 2009. Photo: HJB

This Thursday I will be in Henderson County for a blackberry twilight tour organized by the Henderson County Cooperative Extension office; contact them for location and schedule information. I have already had two calls this week with questions about spotted wing drosophila (SWD) and blackberries, so I will be focusing on that topic and will also touch on thrips and cane borers.

Results for multi state spotted wing drosophila project: what's next for eFLY

Female (left) and male (right) spotted wing drosophila on a raspberry at the Upper Mountain Research Station near Laurel Springs, NC. Photo: HJB

Last fall I solicited help from the readers of this blog and from small fruit growers, consumers, and researchers from throughout the eastern US to rank spotted wing drosophila (SWD) research and extension needs.  You responded in force with over 300 responses to our online and in person surveys.  A group of researchers and extension folks (include myself) used these responses to craft a multi state project, including cooperators from Georgia, Michigan, New Jersey, New York, and North Carolina with connections to projects in many other states, which we submitted to the USDA Specialty Crop Research Initiative Program. We entitled our project eFLY. There is ongoing research activity in the western US on SWD, including the SWD*IPM group coordinated through Oregon State University, but we felt strongly that environmental differences in the eastern US presented very different management challenges for SWD and regionally appropriate research was crucial. This conclusion was borne out in 2011 when monitoring tools and management strategies developed in the western US did not prove effective in the southeast US and continues to be the case in 2012 as we encounter another difficult SWD management season.

Unfortunately, we recently received word last week that our project was not selected for funding.  I don't often share the results of grants with the readers of this blog, but the feedback and participation we received from small fruit stakeholders throughout the eastern US to our request for help was so fantastic that I felt I should share the ultimate outcome with you as well.  Reviewers of our proposal cited our strong stakeholder engagement as a strength of the proposal, which is in no small part thanks to the responses we received from you to our survey.  

What does this mean for SWD research in the eastern US moving forward? 

The goal of developing a multi state project was to answer questions about SWD management and biology throughout the eastern US and to develop near-term implementable SWD management programs.  A project of this scope will be highly unlikely without funding.  A number of the scientists cooperating on this project have some regional or state support to conduct work on SWD. 

Our lab has funds from North Carolina and from the NC Blueberry Council which will support some of our work for this year and part of next summer.  The SWD*VMN will continue at least through 2012, and we hope to continue into 2013.  Beyond this, however, funding is unclear.  We will likely be seeking your feedback again for future multi state projects as well as reaching out to our state and local grower communities to understand their management needs and for continued and further support.  

Please do not hesitate to contact me for more information on SWD in the southeast.

Upcoming pollinator presentation at NC State

Honey bees and native pollinators active in early summer blooms. Raleigh, NC. Photo: HJB

My backyard was a pollinator paradise this morning. Carpenter bees, bumble bees, honey bees, and lots of small native bees were active at our salvia, hydrangea, and kniphofia.  All these bees reminded me that I wanted to share that Shelley Rogers will be defending her master's thesis on pollination ecology in North Carolina blueberries this Tuesday, May 29th at 9am in 3503 Thomas Hall on NC State's campus.  Shelley has done an outstanding job of describing the pollinator community, individual pollinator efficiency, and some of the unique bee interactions specific to blueberries in the southeast.  She'll be sharing the results of this effort Tuesday, and her presentation is open to the public.

Carpenter bee foraging on salvia. Photo: HJB

Do it yourself: An update on distinguishing SWD larvae from other insects in strawberries

Early this spring, I wrote a post discussing how to distinguish spotted wing drosophila (SWD) larvae from other internally feed insects.  That post was focused primarily on blueberries.  This spring and early summer, however, I received several calls about SWD in strawberries, and they appeared in our research plots for the first time.

Fortunately, the majority of grower calls I received about larvae in strawberries ended up being sap beetle larvae rather than SWD larvae.  Sap beetles or picnic beetles are actually a complex of beetle pests which include at least three species in North Carolina (Carpophilus lugubris, Stelidota geminata, Glischrochilus quadrisignatus, and others) and are attracted to rotting, not sound fruit.  If rotting fruit are present near sound fruit, as can commonly happen when you-pickers aren't thorough or rain prevents picking, sap beetle adults and larvae can also attack sound, otherwise marketable fruit.

While sap beetle larvae are also not desirable in strawberries, they are more easily controlled than SWD.  Good sanitation, meaning removal of overripe or rotting fruit, is usually enough to keep sap beetle populations in check.

How, then, can you distinguish between sap beetle larvae and SWD?

Host fruit
Sap beetles will first attack overripe, rotting, or otherwise damaged fruit.  SWD will be found in fruit that appears otherwise marketable until cut open.  As SWD grow older, fruit condition may deteriorate, but fly larvae found in sound fruit are more likely to be SWD than those found in rotting fruit.

Size
Young sap beetle larvae may be similar in size to large SWD larvae, but in general they will be larger than SWD larvae.  Size on its own is not a good determinant, but it can be a good initial indicator.

Sap beetle larva on knife blade. Photo from a commerical strawberry farm in eastern NC, 2012.

 Appearance
SWD larvae lack legs, have no distinct head, lack hairs or bristles, and are tapered on both ends (see here for more images).  Sap beetle larvae have distinctive head capsules, three pairs of legs, and bristles along their bodies.  Adult sap beetles may also be present along with larvae.

Sap beetle larva. Note the three pairs of legs, the distinctive brown to black head capsule and the bristles along the body.  Sap beetle larvae will be mostly white or cream colored and lack patterns on their body. Photo from a commerical strawberry farm in eastern NC, 2012.

Two spotted wing drosophils larvae (center) inside a day neutral strawberry, Upper Mountain Research Station, October 2011. Photo: HJB

What other insects might be present inside strawberries?
Corn earworm (Helicoverpa zea) are occasional pests of strawberries, and the larvae can tunnel into berries.  Corn earworms are caterpillars, which means they have a distinctive head capsule and three pairs of front legs like sap beetle larvae, but they also have short, grippy prolegs along their abdomen and have a pattern of stripes along their body (although their appearance can be highly variable as larvae age).

Corn earworm larvae feeding on strawberries. Photo via UC IPM.

What should growers and homeowners who find SWD do?

I am getting reports of spotted wing drosophila SWD larval activity in some southeastern locations over the past two weeks, and we have observed SWD infestation in some of our research station plots in North Carolina.  Infestations in my plots are a good thing, because it allows us to study SWD here and provide you with up to date information, but infestations in grower fields are another matter. We have been catching adult SWD since January in North Carolina, but these are the earliest larval infestations we have recorded in the state.  This early activity has prompted several questions about what growers or homeowners should do if they find SWD infested fruit.  Here's a quick summary of the four key steps you should take in the event of SWD infestation:

1. Remove all ripe and ripening fruit and destroy it (by freezing, "baking" in the sun inside a clear plastic bag for a few days, or removing from the site).  Eggs or larvae may be present in otherwise sound appearing fruit. Leaving this fruit means that potentially infested fruit is present and could be harvested.

2. Begin an aggressive (once per week if it does not rain, reapplication in the event of rain) spray program.  Rotating between at least two modes of action will reduce the likelihood of resistance development.  See here for information about the probably efficacy of registered insecticides in southeastern small fruit crops.  Because these efficacy ratings are based on work done largely in the western US, where environmental conditions differ, they are not set in stone.  We are running several efficacy trials as I type and hope to have NC specific data by mid summer. 

3. Practice excellent sanitation.  Remove all ripe fruit and sell or destroy it.  Do not discard culls in the field, and clean up after rain and u-pickers. Unpicked fruit is a reservoir for SWD larvae.

4. Sample fruit regularly and consider trapping flies.  Traps tell you SWD presence or absence and are not perfect, but they are helpful.  Place traps in strawberry rows, near fruit for the best chance of catching flies.  Sample fruit each harvest by either cutting them open and looking for larvae, crushing them in salt water (1/4 cup salt per gallon), or freezing them.  Salt water and freezing will cause larvae to exit fruit.  Sample at least 30 berries per field.  See here and here for trapping information and here for larval sampling information.

All growers are strongly encouraged to monitor for SWD adults before larvae are found.  If adults are present and fruit are ripe, pesticide treatments are recommended through the end of harvest.  We hope that this strategy will prevent larvae from showing in fruit and triggering the actions listed here.

Update, June 22, 2012
I am aware that homeowners may be not be able or may prefer not to use insecticides on fruit in the gardens are yard.  Unfortunately, sanitation alone will not eliminate and SWD population.  However, if you can pick your fruit a bit earlier or a bit less ripe, it will be exposed to SWD for less time and will perhaps be at a lower risk of infestation.  It's also important to note that while SWD larvae cause fruit to decay quicker and are unpalatable if present in fruit, they are not poisonous or parasitic.  If you have inadvertently consumed fruit from your home garden that SWD larvae have been present in, they do not pose a heath risk.

Update, August 7, 2012
I have been reading LOTS of scientific papers about SWD in the last week.  A couple of Japanese references suggest that mesh cages or bags (specifically 0.98mm mesh) prevented SWD infestation in blueberries without impacting plant growth.  We use mesh bags a lot to either keep insects we are studying in or to keep insects we don't want out.

We have used mesh bags in blackberries to exclude thrips from developing fruit in order to determine if they impact fruit development.  They don't appear to.

This strategy is worth a shot for homeowners who can tolerate the sight of bags on their plants.  In order to exclude SWD, cages should be placed before fruit begins to change color and tightly sealed at the bottom.  We'll often place a piece of quilting foam between the cage and the stem of the plant to allow us to tightly tie the cage shut (with a zip tie or twine) but protect the stem from damage.  Cages should stay in place until you harvest your fruit.  We use organdy mesh from fabric store and sew our cages to size, but paint strainers also work in a pinch.  I plan to try this method with my backyard blueberries, blackberries, and figs next year and will be interested to hear if others also give it a shot.

What causes misshapen strawberries?

Recently, I've gotten a few questions about misshapen strawberries.  Misshapen or "wonky" strawberries can be caused by several things, but the two most common causes likely to occur in North Carolina are poor pollination and lygus bug injury.  It's actually fairly straightforward to distinguish between these two types of injury.

Poor pollination
Strawberries do not require, but benefit from, insect pollination, so weather conditions that limit insect activity and pollen movement typically precede when this type of misshapen fruit appears.

Misshapen strawberry fruit due to poor pollination (above) and a normal appearing fruit (below). Photo: HJB

Poor pollination causes misshapen fruit because unfertilized seeds remain small and the fruit around them does not grow at the same rate as the fruit around fertilized seeds.  On the image above, the top fruit has seeds of different sizes next to each other while the seeds on the bottom fruit are uniform.

Lygus bug injury
North Carolina Department of Agricultural (NCDA) regional agronomist David Dycus mentioned via email today that growers in Mississippi had recently expressed concern about misshapen fruit due to lygus bug feeding.  Lygus bugs (also known as tarnished plant bugs) feed on strawberry seeds and fruit and can also cause misshapen fruit.  Lygus feeding does not result in variable seed size and can, therefore, be distinguished from poor pollination in strawberries.  Typically, North Carolina growers do not experience extensive damage from lygus bugs, because they are active later in the year.  This year, however, they may be active earlier (although, our warm spring has turned a little chillier), and it's worth keeping an eye for their damage.  Lygus can be difficult to control, so if grower suspect they have damaging populations of lygus present, they should contact their county agent or myself for recommendations.

Strawberries damaged by lygus bugs. Photo: UC IPM Program

Other, non pest, insects can look like lygus bugs, include beneficial insects like big-eyed bugs and non strawberry pests insects like false chinch bugs, and it's important to correctly identify pests.  BugGuide has a nice identification guide for Lygus lineolaris (the east coast species which feeds on strawberries).

Other causes of misshapen berries
Insects and poor pollination are not the only causes of misshapen fruit in strawberries. Pathogens can damage fruit, mechanical injury can scar it, and abiotic factors can change fruit shape.

Update, 27 April 2013
An update to this post has been added to the NCSU Strawberry Growers Information Portal.

Why are monitoring sites only listed by county?

You may have noticed that site names for the SWD*VMN are coded by county followed by a generic number.  I have also shared monitoring data online for the Grape Root Borer*Volunteer Monitoring Network (GRB*VMN) and for blueberry insect monitoring programs run by my laboratory, again with sites identified to the county level. I had a request via the comments on this blog for more detailed location information for one of our SWD*VMN monitoring sites. Because of this request, I wanted to clarify that it is my policy not to provide any geographic information about trapping locations below county.  The reason for this policy is two fold:

1. County is a established level for displaying insect (or other invasive organism) detection information.  See the National Agricultural Pest Information System for an example, and

2. All of our monitoring networks represent a patchwork of public & private and commerical & non commerical land. Because some commerical fruit growers have generously to allowed us, county extension agents, or others to trap on their land or have contributed their trapping data to our networks, we do not want to risk any potential harm to their business by sharing more information than necessary with the public.

The purpose of sharing insect monitoring data online is to provide information growers, homeowners, and other stakeholders can use in making management decisions.  It is not intended to replace site specific monitoring by growers or homeowners.  Just because an insect is being trapping in your county does not mean that it is present on your farm. Knowing exact trapping sites within a county would not change this.  Insect activity in your county does suggest, however, that it would be wise for you to go out and check your plants. Insect trapping data is also not intended for use by regulators or consumers.  Just because adult insects are active at sites does not necessarily mean that damage to crops is occurring.

Eagle eyed readers may have noticed that I will occasionally name a site when posting about trapping data.  I only do this for sites at state and/or university run research stations, like New Hanover 1, which is located at the Horticultural Crops Research Station near Castle Hayne, NC.  Because research stations are non commerical operations, identifying these sites does not compromise grower cooperator privacy.

Spotted wing drosophila adults trapped in North Carolina blueberry country

Spotted wing drosophila (SWD) detections have begun earlier this year than in the previous two years the Spotted Wing Drosophila Volunteer Monitoring Network (SWD*VMN) has been active.   Now in addition to positive detections in Surry, Randolph, and Rowan Counties, SWD has been detected in southeastern North Carolina blueberries for the first time this year.

On April 5th, five male and five female SWD were captured in traps at the Horticultural Crops Research Station near Castle Hayne, NC. This site is New Hanover 1 in SWD*VMN, and you can see data from last year here.  You'll notice that last year, we caught our first fly here on May 9th, a full month later than our first capture this year.  You can see all the trap captures from this site, including those from last week and all future dates here.

What do these trap captures mean for growers in North Carolina?
The fact that we are catching flies at several locations throughout the state means that SWD are active.  This means that growers should be vigilant for both SWD adults and larvae on their farms.  Growers are strongly encouraged to monitor for SWD adults using the same traps we are using (learn how make and use SWD traps here and here).  However, we don't have a good handle on how trap captures relate to fruit infestation, which means that growers should also monitor fruit carefully (learn how to sample fruit and identify Drosophila spp. larvae here).  If SWD are present on your farm, we are currently recommending a fairly aggressive management strategy, because there is zero tolerance for larvae present in marketed fruit. Contact your county cooperative extension agent or Hannah for SWD management recommendations.

The SWD*VMN is supported by the North Carolina Tobacco Trust Fund Commission, Inc. and the NC Specialty Crop Block Grant Program.

More information
Insect monitoring in NC Blueberries - 2011
Spotted wing drosophila adult trapping data - New Hanover 1
SWD*VMN

What to watch for: flea beetles in strawberries?

When Duplin County extension agent John McIntyre called me asking about flea beetles in strawberries, I was skeptical.  Flea beetles are common pests in tobacco & vegetables in North Carolina and one species feeds on grapes, but I had never heard of flea beetles as pests in strawberries.  I figured that whatever damage was present was likely due to our bumper crop of caterpillars or other, more typical pests. However, when he sent me these pictures, it was clear that the beetles pictured were flea beetles or something very similar and that feeding damage was from them.

Two adult flea beetles on strawberry foliage. The "lacy" feeding damage is characteristic of many foliar feeding beetles. Photo: John McIntyre, Duplin County NCCE.

Adult flea beetle with John's figure for size reference. Photo: John McIntyre, Duplin County NCCE.

Also present on leaves and tunneling into at least one strawberry fruit were what appear to be the larvae of these same beetles. After seeing these images, my first thought was that theses beetles looked an awful lot like grape flea beetle, a relatively common early season grape pest whose adults and larvae both feed on developing buds and foliage in grapes.  See here for a nice set of images from Michigan State University of grape flea beetle adults and larvae.  It turns out that grape flea beetle (Altica chalybea) has a close relative known as the strawberry flea beetle (Altica ignita), so it's possible that that these may be either species or a completely different critter.  John brought samples of the larvae and adults by my office this evening, and I'll identify them over the weekend and post an update here.


So, now that I believe we're dealing with a flea beetle, what should the affected growers do?  I do not think that the foliar injury in the images above will result in yield loss, and I suggested that the growers not treat if only foliar feeding was present.  However, one larva John found had tunneled into a strawberry.  If lots of larvae are present and potentially feeding on fruit, this is of much greater concern.  Unfortunately, most of the pesticides effective against flea beetles are broad spectrum and may flare spider mites in strawberries, which have already become problematic in strawberries this spring throughout the southeast.  There is one narrower spectrum material that might work can be organic as well, and I suggested to John that if larvae were present, this might be the best choice.  See a note about pesticide recommendations.

Update, 10 April 2012
I took the adult beetle and larval samples to Dave Stephan, insect identification expert at the NC State University Plant Disease and Insect Clinic this afternoon. Dave agreed that it does indeed look like it is from the genus Altica, but he suspected that they were too small to be grape flea beetle.  He is going to run them through a key to determine if they are strawberry flea beetles or something else entirely!

Spotted wing drosophila captures have begun

The spotted wing drosophila volunteer monitoring network (SWD*VMN) began our 2012 trapping season two weeks ago, and this week brought reports of our first SWD captures in Surry and Randolph Counties.  You can see all of our trapping data, from the beginning of the SWD*VMN in 2010 through present, here.  The 2012 map is below. Click on a county to view data for all the sites in that county.  For counties with multiple sites, you can click on each site's name to data just for that location.  Trapping data are listed in reverse chronological order (most recent first). 

Spotted wing drosophila captures by month, 2012

Alternative content

Legend

January

February

March

April

May

June

July

August

September

October

November

December

Not Found

Because trapping recently began, a number of sites have yet to report their trap captures.  Many locations will be added in the next few days.  If you are interested in participating the SWD*VMN, please contact Hannah Burrack.  Sites are only identified to the county level to protect participant privacy.

The SWD*VMN is supported by the North Carolina Tobacco Trust Fund Commission and the North Carolina Specialty Crop Block Grant Program.

What to watch for: caterpillars everywhere!

Caterpillar feeding on developing blueberry buds. Photo: Bill Cline

Worms or caterpillars, whatever you prefer to call them, there is an bumper crop of larvae in North Carolina this spring.  My colleague, Steve Frank, ornamental and urban horticulture entomologist, spoke to the Raleigh News & Observer this week about about the large number of cankerworms present in state, and this afternoon, I received calls about caterpillar damage in two crops, blueberries and strawberries.  The abundant caterpillar populations are likely due to warm spring weather; many insects have been able to begin an early generation. In blueberries, this has resulted in isolated pockets of large numbers of what appear to mixed populations of spanworms, cankerworms, and other generalist caterpillars.

A diverse assortment of caterpillars from southeastern North Carolina blueberries. Photo: Bill Cline.

 One grower who has noticed large caterpillar populations in Reveille, a later flowering variety, and asked plant pathologist Bill Cline what the potential management options might be.  In the past, blueberries grower may have used malathion, a broad spectrum insecticide, applied in the late evening to control caterpillar populations.  I instead suggest that the grower use a narrow spectrum material that is safer to bees, as the plants to be treated were close to bloom.  Regardless of how safe a pesticide may be for bees, if plants are to be treated during bloom, any material should be applied in the evening minimize exposure to bees and allow for maximum dry time before they begin foraging.

The second question was from a research station in Virginia, where they had noticed green caterpillars present in their ripening strawberries.  My suggestion for strawberries would be the same--select a narrow spectrum, bee safe material.  These would include microbial (such as Bt) or insect growth regulators (such as Intrepid). See a note on pesticide recommendations.  Following any treatment, plants should be carefully scouted for re infestation, since high insect pressure situations may result in more movement into crops.  Just because caterpillars are present in a crop again following treatment does not necessarily mean that the treatment did not work.  Insects can also move back into plantings following a treatment.

What to watch for: A preemptive question about mites and hops

Hop yard in western NC, July 2010 Hop Tour. Photo: HJB

With the news that Sierra Nevada Brewing Company is opening a facility in Mills River, NC, interest in North Carolina hop production has again surged.  I think we still have a lot to learn about the feasibility of growing hops in North Carolina, but several, mostly small scale producers are already active.  One of these growers emailed me today asking about their main arthropod pest, spider mites, and what action she might take to prevent large populations developing this year.  Last year, she released two predatory mite species, Neoseiulus fallacis and Phytoseiulus persimilis, and she was wondering if those populations could overwinter and be relied to provide control this year. 

Hops leaves respond to relatively low mite densities.  The yellow stippled area on this leaf had a population of spider mites feeding on the opposite side. Photo: HJB

 My reply: "We have native populations of N. fallacis in the western NC mountains, so it is reasonable to assume that they should be able to overwinter (although lab reared mites may be less adapted to winter conditions).  We have had success overwintering P. persimilis under high tunnels on strawberries, but I can't say how well it will do out in the open.

The only way to know if your mites from last year have stuck around is to look for them. Sample 10 leaves per variety weekly and observe with a minimum 10x hand lens.  It will take some practice, but you can see and count mites with a hand lens.  You can distinguish predatory mites from pest mites by size (they are smaller), shape (most are tear drop shaped or oval), and color (P. persilimis) is orange.  Predatory mites also move much faster than pest mites. See here for images of some of the predatory mites commonly used for biological control. Start sampling when you have new leaves and continue weekly.  When and if you release additional predatory mites will depend on when spider mite pests appear in your planting."

What to watch for: strawberry update

This morning, I visited our strawberry research plots at the Central Crops Research Station, Clayton, NC.  We will be using these plots for sap beetle, caterpillar, and spotted wing drosophila research this spring, and, like most of the southeast, our plants are pushing early.  It looks as though we will have berries in about 3 weeks, which is a month ahead of our normal schedule.

Along with this potentially early strawberry crop comes early questions about pest management.  I have fielded lots of questions about strawberry clippers and two spotted spider mites in the last few weeks.  I posted several times last spring about strawberry clippers, and you can find those posts here.  You can also find my posts on spider mites from the last several years here.  For grower with spider mite populations at threshold (5 mites/leaflet in a sample of 10 leaflets per acre) and plants that have not yet started fruiting, now is a good time to get those populations under control.  You can prevent mite issues later in the season by treating now with a miticide and avoiding the use of broad spectrum insecticides (pyrethroids and carbamates) unless absolutely necessary for other insect pests. If a broad spectrum material is needed, for example against sap beetle or SWD infestations, scout for spider mites before and watch populations carefully follow a treatment.  For growers who do not have mites about threshold (or no mites at all), you can breathe a little easier--barring a major slow down in plant growth, you may avoid the need to treat at all for mites.  Once plants are actively fruiting and rapidly growing, mite populations must be very high to cause damage--and very high mite populations typically only develop if you start off with mites earlier in year (around now). 

More information
Strawberry clipper posts - NC Small Fruit and Specialty Crop IPM
Two spotted spider mite posts - NC Small Fruit and Specialty Crop IPM