Author Archives: svtaylor

Small upsurge in kudzu bug populations

Kudzu bug has been spotted above threshold (1 nymph per sweep – use at least 15 sweep samples in multiple parts of the field) in south central Virginia and in parts of central North Carolina. Kudzu bugs typically move into soybean in July-August in our state. Distribution surveys conducted by the entomology department in 2016 showed that kudzu bug are present in many soybean growing regions of our state.

Please consider the following information before making the decision to spray for this pest.

  1. Wait until nymphs (nymphs are wingless and cannot fly) are present in the field. Adults can make multiple invasions into a field. You do not want to make repeated sprays for this pest.
  2. Insecticides labeled for kudzu bug are broad-spectrum and will kill beneficials in your field. We are experiencing a large and early corn earworm flight this year in Virginia. Worm pests are much more likely to be a problem in fields that have been previously sprayed.

I’ll keep you posted on what we are seeing in soybean throughout Virginia. Please call if you have something to report.

Sally 919-801-5366

Large bollworm flight this year into VA cotton

If blacklight traps at the Tidewater AREC in Suffolk are any indication, we are currently experiencing an unusually large and early bollworm (aka corn earworm) moth flight this year. Average trap catches over the past 4 nights have averaged 70 moths per night. I have included 2016 season-long catches below for comparison.

We have additionally scouted for, and found, eggs in cotton and on silks of late-planted corn. I have included pictures below to help with identification. Our ongoing corn earworm survey has revealed large numbers of worms completing development on Bt corn in multiple counties. I strongly encourage cotton growers who planted Widestrike or Bollgard II this year to be vigilant when scouting fields. In agreement with Dominic Reisig’s (North Carolina State University) 2016 recommendations, entomologists in the Mid-South (Angus Catchot – Mississippi State University) have suggested egg thresholds broken-down by trait package:

WideStrike Cotton: Treat on 10-15% egg lays on bloom tags

BG2 cotton: Treat on 25-30% egg lay on bloom tags.

These thresholds are supported by observations made across the Southeast last year, including in North Carolina and Virginia, that worms have a higher chance of surviving on blooms than on any other part of the plant. These thresholds have not been established through experimentation and I consider them to be extra protective. Budworm eggs are identical to bollworm eggs and this species is controlled by Bt toxins. I have seen both budworm and bollworm moths in cotton this year.

Some growers have planted conventional cotton this year. We have established egg and larval thresholds in Virginia for non-Bt varities:

Eggs: 10 eggs per 100 terminals or 2 eggs per 100 fruiting forms (most cotton we have scouted has reached this threshold)

Larvae: 3 live worms per 100 terminals or 3% damage to squares, blooms, bolls

Currently, we have experienced no unexpected injury to Widestrike III or TwinLink technologies. I would not assume these varieties to be bulletproof in a high pressure year, but I do think that these technologies offer good protection in our area.

I recommend spending the extra money on a worm-specific product instead of relying on pyrethroids. Vial tests in Suffolk have indicated a trend towards resistance for several years and there have been field failures reported south of us this season. Besiege and Prevathon are good choices because they offer residual control. Besiege targets sucking-bug pests in addition to worms. I have had inquiries about Intrepid Edge. Virginia Tech has not tested this product in cotton. It has performed well in soybean tests and in cotton tests in other regions (Jeremy Greene- Clemson University, South Carolina). Keep in mind that no product works well against large larvae. Due to the early nature of this year’s flight, we may experience additional pressure later this season. I will keep you updated on what’s happening in Virginia. Please call if you have anything to report.

Sally 919-801-5366

 

Aerial applications effective for stink bugs

Last week the entomology department followed up on aerial spray applications for stink bugs. These applications were very effective (>98% mortality). If you are considering spraying for this pest in your corn, NCSU recommends bifenthrin as the pyrethroid of choice. This is consistent with spray trials at the Tidewater AREC that showed poor control with lambda-cyhalothrin (karate, warrior II). All pyrethroid insecticides must make contact with the insect to kill it and there will be poor, if any, residual control. We recommend waiting to treat until all wheat is harvested in the nearby area. So far, there have been no infestations at threshold in corn fields that are greater than 1/4 mile from wheat. Currently, we are scouting Virginia’s eastern shore where the wheat harvest is in progress.

 

Stink bug numbers continue to climb

Brown stink bug numbers have continued to increase in eastern Virginia from the Northern Neck to the Tidewater region. We have scouted fields in Suffolk and Caroline County with higher than threshold infestations spanning the entire field. Infestations in most fields remain confined to border rows and the majority of infested fields are near where wheat has been recently harvested.

Many growers are facing the decision to treat. Previously I had reported a threshold of 1 bug per 4 plants. In order to be extra protective during ear formation and elongation, treatment at the 1 bug per 10 plants threshold can be justified for heavily infested fields. More information about stink bugs in corn can be found here – NCSU corn stink bug management considerations. 

The ability of stink bugs to injure corn depends heavily on corn growth stage. Trials at the Tidewater Research Station have shown that stink bug feeding does not always reach developing ears. The photo below shows a healthy ear developing  (VT growth stage) despite multiple feeding lesions to the outside of the stalk. This may be good news for Virginia growers. We cannot determine if yield was effected in these plants until later this season.

This week, we will be rechecking fields  that were treated with aerial applications and post updates on the effectiveness of these sprays.

 

 

 

Stink bug numbers increasing in corn

Coinciding with the wheat harvest, brown stink bugs have been moving into pre-tassel corn in the southeastern region of our Virginia. The entomology department has scouted fields over threshold in Chesapeake and Virginia Beach. So far this season, stink bugs are present in low numbers in northern, central, and western regions of the state.

Thresholds for stink bugs in field corn are (From Dominic Reisig at NCSU):

one stink bug per four plants during ear formation, elongation, and pollen shed

one stink bug per two plants nearing the end of pollen shed to the blister stage.

Plant injury from stink bugs may include:

Holes in leaves and, in severe cases, twisted plants.

It is important to remember that this bug typically infests on edges of fields and in spotty locations. It is possible, though unlikely, that stink bugs will infest an entire field. Spray volume is critical if you decide to spray – use a high volume to ensure that sprays penetrate the canopy. Insecticides labeled for stink bugs in corn (e.g., Baythroid XL, Karate Z, Warrior II) must come into direct contact with insects to kill them.

 

 

EPA decision on chlorpyrifos

The head of the EPA, Scott Pruitt, signed an order last night denying the petition to ban chlorpyrifos (Lorsban). This decision will allow peanut growers in our area the continued use of this insecticide for the foreseeable future, perhaps until 2022 when the EPA is required to reevaluate safety of this product. The environmental group that filed the 2007 petition to ban chlorpyrifos has announced its plans to appeal the decision.  More information can be found here – https://www.epa.gov/newsreleases/epa-administrator-pruitt-denies-petition-ban-widely-used-pesticide-0

Warm weather and grain bin insects

Our recent warm weather has done more than wake up your plants – it has signaled to many insects that it is time to start feeding and reproducing. Prompted by a call from ANR agent Mike Parrish in Dinwiddie County, I spoke today with Kathy Flanders at University of Auburn about her recommendations to mitigate insect injury in store grain. Her #1 suggestion – turn on those fans! Your goal should be to keep the temperature inside your bin below 60 degrees. Make sure and leave equipment running long enough to cool the entire structure. If you are unable to keep temperatures below this threshold, or if our nights do not stay cool, make sure to take samples regularly to scout for insect injury. Consult this guide for management recommendations specific to the Southeast: http://www.aces.edu/pubs/docs/I/IPM-0330/IPM-0330.pdf.

EPA review of pyrethroids

The EPA is in the process of reviewing some of our older, broad-spectrum classes of insecticides. The comment period is now open for the preliminary ecological risk assessment of pyrethroids. I strongly support the need for continued availability of these materials because they are relatively safe for mammals and biodegradable. Importantly, pyrethroids are the only option for pest control of certain insect pests in some cropping systems. Entomologists, including myself, at universities throughout the Southeast have expressed their support for pyrethroids in a letter to the EPA. However, the EPA is really looking to hear from people that use these products responsibly. The below link provides a tool to make comments on EPA dockets without looking up each product individually. It also includes the type of information that is most helpful and a template to follow if so desired. Comments from our Virginia growers will be much appreciated!

https://www.votervoice.net/PWG/campaigns/48706/respond