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Wednesday, May 26, 2010

National Pollinator Week

National Pollinator Week is June 21-27th.  This is an opportunity to learn more about the insects (and some vertebrates) that make our fruits and vegetables possible.  Pollinator Week events in NC include the Johnston County Pollinator Festival at the Howell Woods Environmental Learning Center on June 26, 2010 from 9:00 am to 4:00 pm. Events include pollinator garden tours, crafts, making bee nesting bundles, visiting with vendors and beekeepers, “What’s The Buzz on Native Pollinators?” classes and beekeeping presentations. Join them for one program, or come out for the whole day. Bring a picnic lunch, see the live animal exhibits, explore the nature trails and experience the beauty of Howell Woods. There is no charge for this event. Howell Woods Environmental Learning Center is located at 6601 Devil’s Racetrack Road, Four Oaks, NC 27524. For more information contact Katrina McDougald at or (919) 938-0115 ext. 115. Find out more about Howell Woods at 

Our lab has developed a strong interest in pollinator diversity and efficiency in the last 2 years.  Shelley Rogers, a MS student co-advised by David Tarpy and I, is studying the pollination ecology of the southeastern blueberry agroecosystem.  Shelley and I will be sharing the preliminary results of this work at the the North American Blueberry Research & Extension Workers Conference in July.  We are hoping to expand our pollinator work to include other production systems, including caneberries, who's pollination needs and pollinators we know little about.

First lightning bugs of the year!

On my drive home last night, I saw my first lightning bug (or firefly) of the year.  Tonight as I walked back from dinner, there were even more active. Fire"fly" or lightning "bug" are both misnomers, as the insects in question are actually beetles in the family Lampryidae.

Fireflies are one of the (many) reasons I am glad to be back east of the Mississippi.  They do not occur in California, where I did graduate work, and summer just isn't summer without them!

Fireflies can also be important predators, as they feed on soft bodied larvae and adults of other insects.  In fact, I have seen fireflies rooting around in blackberry blossoms, presumably in search of larval thrips to eat.  I suspect the plant actually receives some pollination benefit along the way.

Tuesday, May 25, 2010

Small Fruits Field Day - June 22

The NC State Small Fruits Field Day is scheduled for June 22nd at the Sandhills Research Station in Jackson Springs, NC.  This will be a twilight meeting, beginning with dinner at 5:00pm.  The schedule is being confirmed, but will include presentations on muscadine grapes, blueberries, blackberries, and strawberries from entomology (me and others), plant pathology (Bill Cline), and horticulture (lots of folks).

A busy few weeks

The blog posts have few and far between the last two weeks.  That will be changing soon, but it has been a very busy few weeks in the lab.  Tobacco season has kicked into high gear, strawberries are wrapping up, and blueberries are picking.  In the next few days, I will have posts on blueberry maggot trapping, tobacco foliar insecticides, spotted wing drosophila monitoring, and several upcoming extension events.

Sunday, May 9, 2010

What does the short strawberry season mean for pest management?

There has been a lot of news lately about the fast, furious, and fantastic North Carolina strawberry crop this spring.  I have posted about the almost overwhelming harvest at the Central Crops Research Station, which looks to be slowing a bit in the next few weeks.  In fact, most of the heavy strawberry picking in NC should be tailing off by the end of May.  This is good for my research program, since we're moving on to blueberries, blackberries, and tobacco this time of year, but is not necessarily music to the ears of growers or consumers.  We are not seeing lower yields in 2010, just a more concentrated crop.

This short season has some direct pest management implications that growers should be aware of.  First for our key arthropod pest of strawberries, twospotted spider mites.  I have only gotten phone calls from one grower with spider mite issues this spring!  Either you are all comfortable with your management programs, or this was a mild mite year.  My money is on the later, as we did not have a single spider mite in our research plots at Central Crops until mid April, and even then, we had to manually infest to generate the number that were needed for our threshold and efficacy trials.  The low spider mite numbers are due to several factors:  Cold winter weather decreased mite populations and produced very hardy, healthy plants.  Healthy plants do not harbor as high mite populations as stressed plants, and they can better tolerate the populations they do have.  The fast fruiting season also reduced the importance of TSSM.  Fruiting strawberry plants can tolerate higher numbers of mites than young plants.  Finally, the rapid harvest season has likely rendered the use of miticides unnecessary.  Even the most effective conventional miticides take 2-3 week for full efficacy because they act on all mite life stages.   When it appears our season will be winding down in that same amount of time, a miticide treatment is probably not advised.  Of course, there are always exceptions to this rule, and I encourage growers and agents to contact me with questions.

Next, thrips: 2010 has been, as expected, a late thrips year with relatively low populations.  Thrips treatments are likely not justified.  I address other thrips related issues in posts here and here.

Lygus bugs are of the same ilk as thrips this season.  We will be out of strawberry harvest before they are likely to be an issue.

Finally, sap beetles.  These late season pests may rear their ugly heads in 2010 not because we have a long field season which will stretch into to heat of summer but instead because the sheer volume of fruit in a short period of time may result in less thorough picking by both employees and customers.  Sanitation is crucial for sap beetle control and is often sufficient by itself.  Chemical controls should be our last option, but they are available.

Just some of the news stories from throughout the state:
WBTV Charlotte at Hall Berry Farm
WRAL's Go Ask Mom blog on organic strawberries near the triangle 
WRAL and Dr. Barclay Poling at our research plots at the Central Crops Research Station, Clayton, NC
WECT's Strawberry Festival Coverage
WWAY on Columbus County strawberries
Sampson Independent on the large crop
In the Field on strawberries in NCDA's Food to School Program

Don't worry about "strawberry insects"

Rockingham County horticulture agent Kathryn Holmes first brought this video to my attention last month in an email where she asked "do we need to worry about these"?  

I fired off a quick reply that these were larval thrips (probably eastern flower thrips), which we most certainly have in NC but are nothing to worry about and certainly do not warrant washing your strawberries in soap.  We do not typically see fruit injury from thrips in NC strawberries, so I do not generally recommend pesticide treatment for these insects.  See this post from earlier in the spring on thrips.  I was not aware, however, that this video had been picked up by other sources until I was searching for local media stories on the strawberry crop and found WRAL news blogger Monica Laliberte's post on the same topic.  Since this information is being passed around more widely, I decided to write up a short post to clarify the video for those that may be interested.

The video was produced by Star-K Kosher Certification, a company that assists businesses in receiving kosher certification for food products.  Most Insects are not kosher, which explains why they are interested in removing insects.  What does this mean for the rest of us who do not keep a kosher diet?  Nothing new!  We do not have any new non native thrips species recorded recently from NC strawberries, which means that the insects that may be present on our fruit are the same as have always been there.  Many thrips are generalist omnivores--they feed on pollen, plants, and even the eggs of other pest insects.  The larvae are present on strawberries because the eggs they hatched from were laid there.  They will feed for 1-2 weeks (depending on the weather) and then molt to adults themselves and move on to the next host.  Thrips are present in numerous other places in the environment--in flowers, in your lawn, on your peaches, and on your house plants--like many other arthropods.

Strawberries are not washed before packing (to do so would dramatically shorten shelf life), and a good water rinse will remove field dirt and insects.  Those that are not removed are ultimately harmless.  I know I would much rather eat a strawberry rinsed in water with a few remaining thrips (or mites) than one covered in soap residue or one treated with unnecessary pesticides used to assuage the fears of consumers coming across a video like the one above!

Saturday, May 8, 2010

Final tobacco trial transplanted!

Our trial site in Stokes County, NC with newly planted NC 196 flue cured tobacco plants. Photo: HJB

On Wednesday, May 5th, Anna and I traveled to Stokes County, NC to transplant our last on farm tobacco trial for 2010!  It's been a busy transplant season, and we have a lot of tobacco in the ground.

Here's a run down of our 2010 trials (in order of transplant):
  1. Soil insecticide efficacy (wireworms, flea beetles, and aphids) - Border Belt Tobacco Research Station
  2. Tobacco splitworm larval performance trials - Cunningham Research Station & Oxford Tobacco Research Station
  3. Insecticide movement & longevity (2 trials) - Cunningham Research Station & Upper Coastal Plain Research Station
  4. Aphid threshold revision trials - Cunningham Research StationUpper Coastal Plain Research Station & Oxford Tobacco Research Station
  5. Tobacco budworm management in seed production - Cunningham Research Station & On farm in Forsyth County
  6. TSWV & Thrips flight timing trial - On farm at one location each in Craven & Duplin Counties
  7. Tobacco streak virus management trial - On farm in Lee County
  8. Lepidopteran (tobacco budworm and hornworm) management - On farm in Stokes County
In all, we have 19 tobacco trials this summer (6 at Upper Coastal Plain, 4 at Cunningham, 1 at Border Belt, 3 at Oxford, and 5 On farm).  

As you can see, we have a diversity of projects underway.  Some of the key questions we will be addressing in 2010 are the efficacy and longevity of transplant water applications of Coragen, testing additional novel applications of Coragen and Belt, and testing new, unregistered pesticides.  Master's student Monique Rivera will be continuing her work on the behavioral ecology of the tobacco splitworm (Phthorimaea operculella).  Doctoral student Richard Reeves will be heading up our pesticide movement and longevity trials as well as beginning his work on economic threshold revisions with aphids.
Newly transplanted tobacco plants in Stokes County treated with a simulated transplant water treatment of Coragen at 7 fl oz/acre.  Because tobacco setters can be difficult to calibrate for small plot work, we apply transplant water treatments in 2 oz of water immediately following transplant.

I'll be posting updates on these projects throughout the summer!

Cherry fruitworm injury showing up in blueberries

While checking blueberry maggot traps on Friday, May 7th, I noticed the first ripening berries on the year. We are about 1 week out from when most of the growers anticipate harvesting their early varieties.  Blueberries differ from the other small fruits I work on (strawberries and blackberries) in harvest patterns; they are far less delicate and are therefore not harvested as frequently.  I can't imagine how growers could manage 400 plus acres of blueberries each if they had to be picked every other day!

Cherry fruitworm injury on ripe and unripe blueberry fruit in Bladen County, NC.  7 May 2010.  Note entry hole on unripe fruit. The other fruit on this branch appear uninfested. Photo: HJB

These first fruit are a good indicator of the damage to expect, and based on what we saw Friday, 2010 looks like a worse cherry fruitworm year than last year (2009).  Cherry fruitworm (Grapholita packardi) and cranberry fruitworm (Acrobasis vaccinii) are the two most common internally feeding insect pests of blueberries in NC and are also important pests in other blueberry growing regions.  Since I have been at NC State, we have seen more cherry fruitworm injury than cranberry fruitworm.  The biggest difference between the two species with respect to feeding is the number of fruit injured.  Cranberry fruitworm larvae feed on several (3-5 berries) to complete their larval life stages, and their frass is clearly visible between injured fruit.  On the other hand, cherry fruitworm larvae feed on 1-3 berries as larvae.  No cherry fruitworm frass is visible outside the fruit, although injured fruit may stuck to one another where the larvae have tunneled.  Fruitworm injury results in early ripening and fruit drop, so the first ripe fruit will typically show the most damage.

Cherry and cranberry fruitworm eggs are laid after petal fall.  Upon hatching, the neonate larvae tunnel into the fruit and feed.  Because internally feeding larvae cannot be controlled with insecticides, fruitworm larvae are controlled with insecticide treatments timed to petal fall (see the NC Ag Chem Manual for NC recommendations, A note on pesticide recommendations), although the flight timings of both fruitworm moths in NC is not clearly understood.  We conducted fruitworm trapping in 2009 and found that cherry fruitworm flights occur early into blueberry bloom.  This means earlier fruiting varieties may be at greater risk.  The fact that blueberry bloom in 2010 was so concentrated (~2 weeks rather than 3-4 weeks) may also have contributed the high cherry fruitworm populations this spring.

At some locations damage was extensive (nearly every ripe fruit was infested), but no live larvae were found in any of the fruit observed.  This means that the damage will likely not persist in the next round of ripe fruit.  It also means that fruitworms are unlikely to become contaminants this season.  We saw a similar fruitworm infestation pattern in 2008.  These two growing seasons are similar in that decent early spring precipitation was followed by prolonged dry weather.  This dry spring resulted in fruit remaining on plants that would have normally dropped with normal precipitations.  In 2008, however, we had a cooler spring, and slower larval development.  This led to a significant number of cherry fruitworm larvae in harvested fruit which rendered some fruit unusable.  This year, our unseasonably warm spring has led to quicker cherry fruitworm development, and if our observations from Friday hold true, less risk of larvae being found in harvested fruit.

Even if cherry fruitworm larvae are not present in damaged fruit, these fruit are likely still unmarketable and need to be removed post harvest, representing a yield loss.  We need to conduct more research on fruitworm biology in NC.  We have a poor understanding of their flight and egg laying timing, nor do we  know what potential biological control agents are present and the impact our management strategies may have upon them.  There is ongoing cranberry fruitworm populations modeling work in Michigan, but our plant and insect phenology differ greatly.

Sunday, May 2, 2010

Eastern tent caterpillar time

While setting up blueberry maggot monitoring traps 2 weeks ago, a grower pulled me aside to look at what he was concerned could become a plague of caterpillars.

Eastern tent caterpillars had taken up residence in one of his pump houses.  These insects are not necessarily pests of blueberries, although they can feed on Vaccinium.  They are more commonly found in trees creating their characteristic tents.  I do not anticipate eastern tent caterpillars posing problems in blueberries, but if they do, we have tools to deal with them.

Tent caterpillar carnage in an oil leak under the pump.

SWD Trapping: Week 1

Spotted wing drosophila trap kits were sent to volunteers on Tuesday last week (April 27th) and should be placed in the field by this coming Tuesday (May 4th).  I placed our first SWD at the Horticulture Crops Research Station Ideal Track, near Castle Hayne, NC on April 23rd in my recently planted blueberry block.  Our plants are sizing up nicely, and this block is situated in 1.25 total acres of blueberries.
A yeast-sugar lure baited SWD trap at the Ideal Track.  Note the yellow sticky card suspended in the trap.  I forget to include these last week when I placed the traps, and I am interested to see if I will catch many more flies with their addition.  Oregon researchers have found the addition of sticky cards very effective.

An apple cider vinegar baited trap at Ideal.  We are comparing these 2 lure types to see which is the most efficient at initially detecting SWD in the southeast and which is better for monitoring active populations (once the fly is detected).

Today, I checked these traps for the first time, and I was pleased to find no SWD in any of the traps.  I did, however, find several insects which could be confused with SWD when our 18 other locations begin to collect samples.  The traps contained fewer non-target insects than I feared they may, but this may be a function of the trapping location.  North Carolina's blueberry plantings are primarily in acidic soil, often surrounded by pine forests, and these areas may not be the most diverse habitat for fruit feeding insects.  I suspect that as the summer progresses, however, we will catch more non target insects, particularly muscid and calliphorid flies, which in my past experience really like yeast lures. (An olive fruit fly (Bactrocera oleae) trap in California I was maintaining near a horse pasture completely filled up with face flies in 1 much that I couldn't tell there was liquid remaining in the trap!)

So, if I didn't find any SWD, what did I find?  I found what appears to be 2 species of native Drosophila and one species of Tephritid, or a "true" fruit fly.  Both of these groups have characteristics that may result in confusion with SWD, so I took a few photos to help trappers and other interested parties distinguish them.  I have not keyed these other flies out to species yet, but I will update this blog post with that information once I do.

The image below shows the 3 types of flies together.  On either outer side are the female tephritids.  These flies are much larger than SWD and have clearly visible, syringe-like ovipositors (egg-laying devises).  There were no males of this species in the traps this week.  The tephritids could be confused with SWD due to the prominent spots on the ends of their wings.  Remember, however, that female SWD do not have spots on their wings (only the males have spots), so an ovipositor and spots do not go together. 

Flies found in monitoring traps on May 3, 2010.  

The 2 other Drosophila species captured included both male and female flies.  These flies were closer in size to potential SWD, but upon observation of the females under the microscope (at about 10x magnification), it was clear that they lacked the large, serrated blade-like ovipositor of female SWD.  Volunteer trappers, your SWD voucher specimens are an invaluable comparison tool for identifying females.  Use them!

A non-SWD female from monitoring trap (top) and a voucher SWD female (below).  Note the difference in ovipositor size and appearance, even at this low magnification (about 5x).

A few other helpful hints for volunteer trappers:
  1. 12 oz appears to be sufficient liquid for 1 week.  I did have to refill all of my traps today (water added to the yeast-sugar lure and more apple cider vinegar added).  We will change lures every 4 weeks, so just refill for the first 3 trap checkings.  This means you will all likely need more vinegar sooner rather than later.  Contact me for refills.
  2. Remember to use 2 different filter containers, one for each lure.  We do not want to cross contaminate.
  3. If non-target insect numbers remain low, in-field trap check time is about 20 minutes for 6 traps.
  4. I suggest changing your sticky card last--after filtering your lure and placing your insects of interest in alcohol.
  5. There's no need to save beetles or moths in alcohol for ID in the lab...we know they are not SWD.
Finally, once all of our trappers have a week of data in, we will be posting live updated graphs of trap captures.  I will link these graphs through this blog.  Look for them the week of May 10th!

Sponsored by the Southern Region Small Fruit Consortium, Project 2010 E-01.