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.

Sunday musings about insects & hops

While sending an email to a colleague about insect & hops in North Carolina this morning, I started thinking about the context in which I get questions about insects, especially in new or speciality crops.

From my email, "I think folks focus somewhat on insects and diseases because these are things we have management tools, and answers, for. The harder question to answer is if a crop itself is ready to be grown where people want to grow it. We can recommend a pesticide or cultural strategy for insect management, but we don't know if there are any hops varieties (or other new crops) that will grow well (or well enough to be commercially profitable) in our state. I would rather see this question as the focus of the conversation rather than 'spray X' or 'release predator B'."

Japanese beetle feeding at the Lake Wheeler Hop Yard, 2010. Photo: HJB

The insect questions still arise, however, but I think these need to be pragmatically address in the context of a still unproven agricultural system. Japanese beetles are a common insect seen feeding our hop yard at Lake Wheeler, and I commonly get questions about them from beginning hops growers. I don't think Japanese beetles require treatment unless they are feeding extensively. If mature (second year or older) plants have so little foliage that JB feeding seriously threatens defoliation, the problem is not JB--it's plant vigor, and all the big guns thrown at the beetles are not going to produce a viable crop. Grapes are an excellent example of this--JB feed at the top of the plant, and as long as they don't go below the top trellis wire and are not in fruit, growers do not need to treat. That foliage will be removed anyway. For first year plantings, the scenario is different, but folks should distinguish between baby plants and mature plants in terms of JB management.

Browning on developing hops cones. Photo: HJB

Another insect I got a lot of questions about last year was thrips. We have extremely high thrips populations in the SE, but I have yet to see thrips in cones at Lake Wheeler. This means that the cone browning observed is unlikely to be thrips injury and is more likely to be due to uneven aging associated with our early and prolonged flowering period. I'd hate to see anyone treating for thrips in hops based on cone browning, especially if the browning is observed in the oldest cones.

My thought process around pest management in emerging and new crops is evolving, but sustainability, environmental & economic, remains the key driver of my pest management philosophy. Understanding pest biology is important, but more important is the feasibility of the whole agroecosystem. Although one factor can sink a farming system, everything must work in harmony for it to succeed.

Insect activity beginning in the research hop yard

Caterpillars feeding on a hops leaf at the Lake Wheeler Field Laboratory. Photo: HJB

Yesterday, undergraduate intern Mandi Harding and I visited the research hop yard at the NC State Lake Wheeler Field Laboratory to check the traps we placed last week, collect mite & aphid samples, and observe any insect activity. The plants are just starting to reach to the top of the trellis, so I didn't necessarily expect large insect populations. I was correct in that there was minimal activity, but we did see some notable insects eating hops or eating other insects that were eating hops. Several plants had recently hatched caterpillars (see above) present, and they all appeared to be the same species. Rather than collecting these larvae and rearing them in lab, we are going to keep an eye on them in the field and collect them when they are closer to pupation.

There were also plenty of beneficial arthropods (insects and mites) present, including lady beetles, predatory mites, minute pirate bugs, and lightning bugs (which are actually beetles and are one of my favorite things about living east of the Mississippi). Thrips were clearly visible crawling on leaves and inside cones. Thrips are potential pests of hops in the southeast, and I am always amazed at the sheer number of thrips present in the early summer in North Carolina. I am even more impressed when I talk to cooperators on research projects in the Pacific Northwest who catch on the order of 10-15 thrips per trap, and we catch 0ver 300 in the same time period. Thrips seem to thrive here, for better or worse. Also thriving are thrips predators, like the lightning bug (beetle) below.

A lighting bug feeding on thrips on a hop leaf. Click here to enlarge this image for a better view of the distinctively striped soybean thrips highlighted. Photo: HJB

We'll be collecting samples and observing insect populations in the hops yard throughout the summer and will post updates when interesting insects appear.

New thrips flight prediction tool now available

Tobacco plant with systemic TSWV infection in a research plot; Craven County, NC, 2008. Photo: HJB

For the past 2 years, a group of NCSU entomologists and climate scientists have been developing a website designed to predict tobacco thrips (Frankliniella fusca) flights and make management recommendations to suppress tomato spotted wilt virus (TSWV) in tobacco.  We are proud to roll out this tool for tobacco grower, cooperative extension agent, and crop consultant use today! The TSWV and Thrips Exposure Tool for Tobacco uses temperature and precipitation data to predict tobacco thrips flight timing.  We then provide management recommendations based on grower provided transplant dates. 

Why do we need a tool to predict thrips flights?
Losses in tobacco to tomato spotted wilt virus (TSWV), which is vectored by thrips, vary greatly depending on year and location, with losses since 2000 in NC alone ranging from several million to over 45 million dollars per year.  In addition to killing young plants, TSWV reduces the uniformity, yield, and leaf quality of infected plants that are not killed. Tools for managing TSWV in tobacco are limited and must be applied before TSWV spreads into the crop. Imidacloprid (Admire Pro®) and Actigard® applied to transplants in the float house are the most commonly used TSWV management measures. However, the level of TSWV control provided by these materials has been inconsistent. 

Field studies at multiple sites in NC and GA have confirmed the value of using both Admire Pro® and Actigard® in reducing losses to TSWV. Results demonstrated that condition of the plants when float bed applications of either product were made influenced the degree of phytotoxicity, with the highest and most persistent levels of phytotoxicity always associated with the weakest transplants. Phytotoxic effects of pre-transplant applications of Admire Pro® and Actigard® can be minimized by applying them separately at least 1 day apart.  These studies confirmed that the greatest reduction in TSWV can be obtained when Admire Pro® (applied as a float tray treatment) and Actigard® are used, and demonstrated that the most effective application timing of Actigard® varies with year and location depending on when the spring flight of tobacco thrips and spread of TSWV occur. Tobacco thrips are the most important species for TSWV transmission in North Carolina and much of the southeast.

How do we know that treatments timed to predicted thrips flights are effective?
Field trials conducted by NCSU entomologists for the last 3 years and Clemson entomologists for the last 2 years have demonstrated that Actigard® treatments timed to thrips flights lower TSWV incidence.

Who should use this tool?

The TSWV and Thrips Exposure Tool for Tobacco should be used by tobacco growers in high risk TSWV areas in North Carolina. An area is considered high risk if it has a historical average TSWV incidence over 10%.

Distribution of tomato spotted wilt virus in North Carolina (based on county reports 1993-2008). The darker colors represent counties where TSWV incidence may be high (10 – 15%) in several fields every year.  Figure from Mina Mila, 2011. Flue Cured Tobacco Information, Chapter 8. Managing Diseases.

How do growers/agents/consultants use this tool?
For example, growers in high TSWV risk areas enter their location, tobacco type grown, anticipated transplant date, and any known or planned greenhouse treatments.  The models then predict, based on grower location, if tobacco thrips are expected to fly within the next 2 weeks.  If thrips flights are predicted, then the website suggests possible management options.  For example, if the predicted flight is within 2 weeks of transplant, a greenhouse treatment of Actigard® will likely result in the greatest TSWV suppression. On the other hand, if the thrips flight is predicted 3 to 4 weeks after transplant, a field treatment of Actigard® may be most effective.  Finally, if thrips are not expected until 8 weeks after transplant, treatment is likely not needed.  Of course, whenever using pesticides, always read and follow the label.  The label is the law! 

Thrips flight predictions are only available 2 weeks out at this time due to forecast data available.  As weather forecasting tools improve, so will the prediction length.

What if I am not in North Carolina?

We have tested the website in South Carolina, and predictions are reasonably close to those for North Carolina.  However, we have not tested the website in another southeastern states, so for the time being, we are recommending it only for use by North Carolina tobacco growers.


What if I grow other crops affected by TSWV?
Tobacco thrips may not be the most important vector in other crops affected by TSWV, such as peppers and tomatoes, so our models are intended only for use by tobacco growers.  We plan to expand these models for other crops in the future.

More information
TSWV and Thrips Exposure Tool for Tobacco
North Carolina State Climate Office
Tomato Spotted Wilt Virus - University of Georgia
Admire Pro - Product Label
Actigard - Product Label


We gratefully acknowledge the support of the Tobacco Research and Education Council, Inc., Altria, Phillip Morris International, and the R.J. Reynolds Fund for Excellence in developing and delivering the TSWV and Thrips Exposure Tool for Tobacco.

Hops in the southeast - a learning experience

Before there are cones, there are flowers. A hops bine as it begins its climb. Photo: HJB

I've recently connected with a group of NC State researchers working on hops production in NC and have begun arthropod surveys in the NC State research planting at the Lake Wheeler Research Farm and several grower locations in western NC. This Monday, I took a trip out to Lake Wheeler to see what might be moving around.

Developing hops cones, the harvested portion of the bine. Photo: HJB.

The most obvious pests currently present are Japanese beetles. This polyphagous, invasive insect is a voracious feeder on many commonly grown ornamental and food crops and appears to have developed a taste for hops.

Japanese beetle injury on hops foliage at Lake Wheeler. Photo: HJB

Beetle feeding along hops bine. Photo: HJB

Several of the bines had Japanese beetle injury on their foliage, and Rob Austin, NC State Soil Science, had treated with carbaryl (Sevin) dust, the white powder visible in the image above. Carbaryl and other conventional broad spectrum insecticides can be very effective against Japanese beetles (a note about pesticide recommendations), but organic pesticide options are limited. Many hops growers are interested in organic production. We do not know how severe of a pest Japanese beetles will be in hops, nor how much summer defoliation is "too much". So at this point, we do not have treatment recommendations for this pest.

As effective as carbaryl is for Japanese beetle, this material has the potential to flare spider mites, which can be an important and difficult to manage pest of hops. If Japanese beetles are present, scout carefully for mites before choosing which material to treat with. We have been monitoring spider mites at 2 western NC hops farms and have found very low populations to date. The populations at Lake Wheeler are higher, and Rob plans to follow up with a mite treatment this week.

Browning on developing hops cones. Photo: HJB

On Monday, we also noticed browning on the tips of developing cones, which several growers have also commented on. In western NC, this injury appears to be thrips related, although there were very few thrips at Lake Wheeler this week. I have also seen some online resources which have suggested that browning can be a sign of approaching harvest.

Arctiid moth caterpiller feeding on hops. Photo: HJB

Caterpillars of several generalist moth species have been observed in hops plantings this spring and early summer. Eastern coma caterpillars were found at several mountain farms, and were subsequently treated with Bt. I found the arctiid (tiger moth) caterpillar in the above photo on Monday. I do not think these generalists are of pest concern at this time, but may be locally problematic.

Young bines at Lake Wheeler. Photo: HJB

A hops field tour, which I will be participating in, is scheduled for July 31 in western NC. As this date approaches, I will be sharing more information.

More information

NC Hops Blog

News & Observer Profile

WNC Vegetable and Small Fruit News - Hops Information Page

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!

What to watch for in 2010: Thrips

Over the next few weeks (0r until the field season gets busy), I will be posting pest watches for 2010. These are designed to provide updates on pests that may be problematic or for which management strategies may differ in 2010.

First up is a group that has become near and dear to me in the last 2 years: Thrips!

Western flower thrips (Frankliniella occidentalis), www.bugwood.org. Photo: J.T. Reed

Thrips as pests

Thrips are of concern to southeastern growers for 2 reasons: 1. They vector potentially devastating plant viruses, and 2. Thrips can directly damage crops in their own right. In the cropping systems I work in thrips are both virus vectors (tobacco and caneberries) and cause direct fruit or plant injury (strawberries, blueberries, and grapes).

In tobacco, thrips vector Tomato Spotted Wilt Virus (TSWV) which can result in significant losses. Colleagues in the NC State Entomology Department developed a degree day model which predicts tobacco thrips (Frankliniella fusca, the most important TSWV vector in the southeast) flights. We have adapted these models for a website that will be launched for use by county agents and select growers this Thursday, April 1st.

Flue cured tobacco plant infected with TSWV. Photo: www.bugwood.org.

Thrips also vector Impatiens Necrotic Spot Virus (INSV), which infects many plants, including caneberries. Caneberry viruses are the topic of a multi state USDA Specialty Crops Research Initiative (SCRI) project with which I am involved. Lead by the University of Arkansas, this project is designed to identify and development management strategies for virus complexes in caneberries. Unlike many other plant-virus pathosystems, caneberries are often infected with 2 to 3 virus before they show symptoms. The virus complex appears to vary regionally, as do the likely vectors.

Blueberry fruit damage caused by thrips oviposition (egg laying) and feeding. Photo: Insect Management in Blueberries in the Eastern United States, Tuner & Liburd.

In strawberries, grapes, and blueberries, fruit injury by thrips is of greatest concern. Thrips feeding on blueberry can also damage blooms. Blueberry injury by thrips is weather and variety dependant in NC. Late blooming varieties (rabbiteye and northern highbush) are more prone to damage, but growers generally do not need to treat these varieties every year. Thrips injury to strawberries is rare in NC, and other injury is often misdiagnosed as thrips-caused.

Thrips can cause bronzing near the calyx in strawberries. Photo: Jack Kelly Clark, UC IPM Program.

Thrips do not cause malformed fruit. The damage in this image is due to lygus bug injury, but malformed fruit can also be caused be poor pollination or dried calyx disorder. Lygus bug injury is also rare in NC and has only been observed on late season or day neutral strawberries. Photo: UC IPM Program.

Thrips injury to grapes is more common in NC than injury to blueberries and strawberries. Grapes bloom and develop later in the spring, when thrips populations have built to higher numbers and are less susceptible to spring weather conditions.

What to watch in 2010

Thrips management in 2010 will be different than in a typically year, because we will likely have fewer thrips than normal and they may move into crops later. If this holds true, we may have fewer problems with thrips in tobacco and small fruits in 2010 than in a typical year.

Tobacco thrips models currently indicate that this spring will have low numbers of thrips. This is not surprising because cool, wet weather negatively impacts thrips during March and early April. This spring, much like last year, has been both cool and wet, until recently. It is possible that weather patterns could become more favorable for thrips, but unless the weather changes dramatically (rapidly warming and drying), I suspect that thrips movements will occur later this year and that populations will be lower than normal.

What does this mean practically? I anticipate that thrips treatments in blueberries may not be needed, and that strawberry injury may also be rare. As always, SCOUT and SAMPLE before making any treatment decision!

We continue to track and model tobacco thrips populations, and we will not have concrete predictions until the end of April, but I will continue to update as this picture becomes clearer.