SWD trap captures now available

Our spotted wing drosophila monitoring locations have been trapping since May in most cases, and now our trapping data is available online. The links below lead to a figure for each site, which are updated as new data are entered. Right now, these figures all look the same since SWD trap captures have been 0 for each site until recently. Two of our locations, one in SC and one in NC have detected SWD, but these data have not yet been entered in the online database. Look for post early this week with the details of these trap captures. I will also be posting a map with links to these locations early next week.

For ease of display, dates are converted into ordinal dates (the number of the date in the year). See here to convert an ordinal date back to a calendar date. If a figure says "no data", this means that trap captures from that site have not yet been entered, not necessarily that there is no data at this time.

Monitoring locations by state (in order from East to West):

South Carolina Locations

Charleston County, SC

Barnwell County, SC

Lexington County, SC. Site 2

Lexington County, SC. Site 1

Saluda County, SC

Spartanburg County, SC

North Carolina Locations

Brunswick County, NC

Edgecombe County, NC

Wanye County, NC

Johnston County, NC
Lee County, NC

Montgomery County, NC

Randolph County, NC, Site 2

Randolph County, NC. Site 1

Davidson County, NC

Gaston County, NC

Cleveland County, NC

Alexander County, NC

Wilkes County, NC

Henderson County, NC. Site 1
Henderson County, NC. Site 2 (This site was established by Dr. Jim Walgenbach at the Mountain Horticultural Research Station on 9 September 2010 in response to nearby trap captures and resulted in immediate detection.)

Virginia Locations

Frederick County, VA. Site 1

Frederick County, VA. Site 2

Montgomery County, VA

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

Reminders!

Our second SWD webinar is tomorrow at 2pm. See here for details and email Hannah for more information.

The NC State Tobacco Tour is July 19-21. Find the schedule and register here. Registration closes Friday!

Grape root borer captures in NC vineyards

Mating pair of grape root borer moths (female, left; male, right).  Photo: H C Ellis, University of Georgia, Bugwood.org

Two North Carolina vineyards have reported grape root borer (Vitacea polistiformis) trap captures in the last week.  Both vineyards are in the Yadkin Valley, where many of our wine grape growers are located.  If these places are capturing moths, they are likely active in other vineyards in the area.  Many wine grape growers do not monitor for grape root borer, so we do not have a good sense of how wide spread they are NC, but they are capable of infesting grapes throughout the state (both bunch/wine grapes and muscadines) and occur throughout the eastern US, from Florida through Ohio.

Grape root borer injury.  Photo: James Solomon, USDA Forest Service, Bugwood.org

Grape root borer larva.  Photo: Clemson University - USDA Cooperative Extension Slide Series, Bugwood.org

Grape root borers are potential devastating pests.  As their name suggests, the larvae of grape root borers feed on the roots and crowns of vines.  Like related species (ie. raspberry crown borer), larvae may live for 1-2 years, longer in northern latitudes, and shorter in southern.  According to Tennessee entomologists, larvae there take 22 months to develop on average.  This same Tennessee factsheet has a great overview of grape root borer biology.  Briefly, egg laying begins about 8 days after emergence, and the eggs take 14 days to hatch.  Eggs are laid at the soil surface.  These newly hatched larvae are the most easily controlled life stage, and chemical treatments (if used) are targeted to them.  Once the larvae enter the roots, they are very difficult to control.  Adult control is also impractical, because the moths do not feed on grapes and therefore would not contact insecticides applied the crop.  Adult moths emerge and lay eggs over a relatively long period of time as well, further complicating management. 

Much of this difficulty arises from the materials registered against grape root borer.  Only one conventional insecticide, Lorsban (chlorpyrifos) is registered.  Lorsban has a long pre harvest interval in grapes (35 days in bunch grapes).  Because moths may continue to emerge until fall, this application timing may be too early in some cases.  Ideally, a material which could be timed to moth trap captures would be more useful.  Identifying an alternative to Lorsban with a shorter PHI is a high priority IR-4 project, but the long life cycle of this pest slows this process.  Non chemical management tools are also available.  Entomopathogenic nematodes and pheromone-based mating disruption (essentially confusing male moths) have shown promise experimentally, but neither have been brought up to commerical scale.  Cultural control by soil mounding (in early July or the start of moth emergence, whichever comes first), can also reduce moth numbers.  Soil mounded around the base of vines creates a longer distance for emerging moths to travel, and they die before reaching the surface.  See the Southern Regional Small Fruit Consortium's Bunch Grape IPM Guide for specifics on treatment options.

Monitoring

Pheromone lures attractive to male moths can be used to detect adults, and these are traps growers have caught moths in this year.  Several trap types can be used in combination with these lures (typically rubber septa impregnated with pheromones), but the easiest to use is probably the bucket trap.  These traps are available from several suppliers (some are listed below).

 

Grape root borer monitoring trap.  Traps are baited with a pheromone lure attractive to Photo: Insect pests of grapes in Florida

Although the grape root borer pheromone is relatively specific, one related species can also be attracted to the traps.  The squash vine borer (Melittia cucurbitae, below) is easily distinguished from grape root borer.

Squash vine borer adult are orange rather than yellow/brown like grape root borers and have more bristles on their rear legs.  See here for another useful image.  Photo: Purdue University Cooperative Extension

In addition to traps, which attract male moths, growers should also scout for pupal cases under the vines.  This will provide a better sense of the total moths present in the vineyard, as traps may pull males in from nearby plantings or wild grapes.  Other states have used pupal case counts to develop treatment thresholds.  Kentucky entomologists recommend treating when 5% of vines have pupal cases present.  Thresholds are an important component of an IPM program, because there are consequences (economic, environmental, etc.) to each management decision, and unnecessary treatments should not be made.

Trap sources

Great Lakes IPM

Trece, Inc.

Gempler's

ARBICO Organics 

Grape phylloxera in NC vineyards

Vidal Blanc grape leaves heavily infested with the foliar form of grape phylloxera at RayLen Vineyards, Mocksville, NC.  Photo: Turner Sutton

This Wednesday, I received an email from Steve Shepard, vintner at RayLen Vineyards, describing a large infestation of the foliar form of grape phylloxera in his Vidal Blanc block.  Vidal Blanc (or just Vidal) is a French hybrid grape widely planted in the eastern US because of its cold tolerance.  I made plans to visit the vineyard next week and was not too concerned about the potential for damage.  Then I received an email from Turner Sutton, NC State plant pathologist, who sent me a photo of the damage (above).

Grape phylloxera (Daktulosphaira vitifoliae) is an aphid like insect which can feed on both leaves and roots of grape vines. Foliar infestations of grape phylloxera are fairly common in NC, but they are usually limited to a few galled leaves and do not impact photosynthesis.  If only a few galls are present, removing the affected leaves before the galls spread can limit an infestation.  In fact, phylloxera was of so little concern last year that we did not address its management in the Southern Region Small Fruit Consortium Bunch Grape IPM Guide. We are meeting to edit this guide in 3 weeks, and adding phylloxera will on the top of my list of changes.  The root feeding form of phylloxera has received most of the attention as a pest because of its potential damage to western US grape plantings and its history as an invasive species in France.  Native North American grapes are naturally tolerant to root feeding by phylloxera, but native French varieties were not.  The use of American root stocks grafted to French varieties (developed by pioneering American entomologist Charles Valentine Riley) is credited with saving the French wine industry.

Foliar phylloxera has become increasingly common in recent years, and infestations as severe as the one at RayLen can reduce photosynthesis therefore decrease fruit quality and vine vigor.   French-American hybrid grapes are being planted more frequently in the eastern US because of their tolerance to varying climatic conditions, but many of these varieties appear more susceptible to foliar phylloxera.  The grape phylloxera life cycle is very complicated, but the stage most amenable to management are the crawlers, which move on the plant surface to found new galls.  Not all the galls on the leaves in Turner's photo necessarily contain live phylloxera, as the galls will remain after the insects have moved on.

Comparatively little work has been done on foliar phylloxera, but Dr. Donn Johnson at the University of Arkansas has put together an excellent fact sheet on phylloxera biology and management.  Dr. Johnson also works with Missouri wine growers, who have been dealing with damaging foliar phylloxera infestations for several years.

More information
Biology and management of grape phylloxera - Johnson, Sleezer, and Lewis

Floating Sheep tackles tobacco again

 Floating Sheep, a geography blog which I have posted on before, has another series of maps related to tobacco.  This time they are comparing crop production and consumption using Google Maps.  In a post here, Matthew Zook, an associate professor of geography at the University of Kentucky, compares mentioned of several crops over geographic areas.  In the US map above, there's a clear tobacco (purple) cluster in the southeast, although tobacco shows up in keyword searches nationwide.  This map is similar to their "minor vice" map, which compared alcohol, caffeine, and tobacco references in the US and worldwide.

Blackberry borers can mean big problems

Weakened blackberry plants, Guilford County, NC. Photo: Gina Fernandez

NC State caneberry specialist, Gina Fernandez has just returned from sabbatical and has wasted no time getting out for field visits. Yesterday, she brought me several samples from blackberry fields in Guilford County that were in severe decline. Their problems were almost all insect related. There were more cane boring pests from these few sites than I have seen my entire time at NC State! I'd like to use these samples as an overview of the key cane boring insects in NC, what symptoms to look for, and what the management strategies for these pests should entail.

Evidence of borer damage is often visible from a distance. Plants will appear weakened, and in the case of raspberry crown borer, floricanes will be loose and easily removed. There are 3 key cane boring insects in North Carolina, and these locations had all of them!

Rednecked cane borer
The rednecked cane borer (Agrilus ruficollis) is part of a family of beetles known as metallic wood boring beetles. The adults lay their eggs on the surface of primocanes and the larvae bore into them. When used, insecticide treatments target the adults, since the larvae do not spend time outside the plant. Larval rednecked cane borer feeding produces galls on the canes. The larvae are flat and found within the cane. As they grow, larvae will tunnel above the gall and reduce plant vigor and yield.

Rednecked cane borer galls (top), larva in gall (middle) and outside of gall (bottom). Photos: Gina Fernandez (top), HJB (middle, bottom).

Low levels of rednecked cane borers can be managed with cultural control, specifically by removing and destroying all infested canes during the fall. The larvae overwinter inside the cane, so pruning will remove next year's generation of adults. For large infestations, chemical control of the adults may be necessary (see the Southern Region IPM Guide for chemical information). Dr. Donn Johnson, University of Arkansas fruit entomologist, has also had success removing primocanes in the early summer after the adult beetles laid their eggs (a June removal date worked the best in Arkansas and did not impact fruiting). This strategy may work well in North Carolina, because our long growing season allows plenty of time for primocane regrowth.

Raspberry cane borer

Raspberry cane borers (Oberea bimaculata), members of a family known as long horned beetles due their prominent antennae, were also present in the Guidford County plantings. The adult beetles create paired girdles at primocane tips in summer. These tips wilt and will eventually fall off, and the entire cane may die. Larvae tunnel downward from the tip and have a 1-2 year life cycle in the southeast.

Raspberry cane borer girdling. Photo: Gina Fernandez

Cultural control, via pruning, is also an effective means of managing raspberry caneborers. Insecticide treatments may be targeted to the emerging and ovipositing (egg laying) adults just after bloom in cases where large infestation exist.

Raspberry crown borer

Raspberry crown borer (Pennisetia marginata) is perhaps the most severe pest of caneberries in the southeast. The larvae of this clearwing moth feed on the roots and crowns of caneberry plants and can kill an entire plant. Because they spend most of their 1-2 year larval stage underground, they are extremely hard to manage. Work conducted in Arkansas demonstrated that late fall or early spring soil drench pesticide treatments are most effective at reducing raspberry crown borers. These timed treatments target the early instar larvae before they are ensconced in the crown. Insecticides are, at this time, the most effective means of raspberry crown borer management. Infested plants should be completely removed, since mature larvae will not be impacted by pesticide treatments.

Raspberry crown borer damage (t0p) and larvae in a blackberry cane (bottom). Photos: Gina Fernandez (top), HJB (bottom)

In addition to the damage caused by these 3 wood boring insects, there were also several canes with damage at the tip that were dying back.

Unidentified damage at cane tips and associated tunnels. Photos: Gina Fernandez

It is possible that this damage was cause by raspberry cane borers, but no larvae were found in the canes, and what tunnels there were stopped several inches from the top. If this was raspberry cane borer injury, we would expect to see tunnels continuing to the soil level or larvae present. These canes may have been injured during tipping and then feed on be opportunistic secondary pests. I dissected one of these canes, and there was fungal growth in the gallery, although this may also be secondary.

Fungal growth in damaged cane. Photo: HJB

Wood boring insects are a fact of life for caneberry growers and can easily get out of control if a planting is not managed carefully. There are abundant feral and wild brambles in the landscape, which serve as hosts for all three of these insects. Carefully scouting, good cultural management, and insecticide treatment when needed will keep borers from destroying caneberry plantings.

More information
Rednecked cane borer - Virginia Tech
Rednecked and raspberry cane borers - University of Kentucky
Blackberry Insect Pest Management - Presentation from Donn Johnson, University of Arkansas

NC vineyard profile

Raffaldini Vineyards & wine maker Stephen Rigby are profiled at Architects & Artisans in two stories. One on the vineyard, and one on wine making. They're worth a look.