As of June 29, we have tested a total of 687 corn earworm moths in our pyrethroid resistance monitoring program and the results are rather foreboding. If you open the attached PowerPoint graph you will see the data from 2010 and 2011, to date. We are seeing levels of survivors reaching 40%–not good for this early in the season. Of course things could change as we move into the season. But recent history has shown that once survivorship reaches these levels, although there will be some ups-and-downs, the overall levels will stay pretty high. The areas of the state where conditions remain dry will be at the greatest risk to intensive moth flights and the potential for less-than-satisfactory levels of control with pyrethroid insecticides.
Additional information: cew-avt-data-jun-29-2011-herbert-pptx
Author Archives: Ames Herbert
Plant bug in cotton, product choice and restriction on Bidrin use
We are seeing a few more fields than usual with plant bugs and damage. According to Johnny Parker with Commonwealth Gin, the number of fields reaching the threshold is about 3-5 percent, and that is based on his surveying about 100 fields over the past week. Since fields are still in the pre-bloom stage, thresholds are based primarily on square retention: Do not let fields drop below 80%. Plant bug damage is distinct and pretty easy to see. Bugs prefer to feed on the small pinhead terminal squares causing them to turn black and shed. You can find the tiny black squares (hit the ‘More’ button to see the image) or the scar where the square was shed. We do not have a lot of experience doing insecticide trials with plant bugs so I called one of my colleges in a state that deals with a lot of plant bug pressure. He recommends using only the insecticides in the neonicotinoid class (e.g., Admire Pro @ 0.9-1.7 oz, Belay @ 3-4 oz, Centric, @ 1.25-2.0 oz) and that they are effective. For resistance management and fear of flaring secondary pests, they recommend avoiding use of either pyrethroids (e.g., Bifenthrin, Karate, Baythroid) or organophosphates (e.g., Bidrin, Orthene). And, he reminded me that Bidrin CANNOT be used during this pre-bloom period. These are the statements on the labels (Bidrin: Early Season—Emergence to pre-square; Late Season—First bloom to 30 days prior to harvest) (Bidrin XP: Use only after cotton reaches the ‘First Bloom’ stage of growth).
Additional information: tpb-square-damage-herbert-doc
Stink bug update
Following a bit of local news coverage about the brown marmorated stink bug (BMSB) and its potential to become a problem in our coastal plain region, I have received numerous contacts from local homeowners/gardeners. To date, of those that have been able to provide insect samples, none have been the dreaded critter. Most have been either our native brown stink bug, or the squash bug, which is beginning to attack squash plants throughout the region. Although damaging, we understand these insects and know how to manage them…as opposed to BMSB which would pose a much bigger challenge. So for now, the good news is that BMSB has not been reported attacking crops in our area…yet. Locals are encouraged to send in suspected samples for ID (Attn: Ames Herbert, Tidewater AREC, 6321 Holland Road, Suffolk, VA, 23437). We recommend that folks put any bugs-in-question into a zip-lock sandwich bag and into the freezer. When mailing, just pad them to prevent breakage during the delivery process.
Corn earworm update
Although we are beginning to catch a few more moths than last week, we are still between generations. If things go according to previous patterns, the second generation will peak at a time to coincide with when field corn is developing ears. Some fields are beginning to tassel, so it won’t be long. We will be tracking and posting our trap catch and AVT (adult vial pyrethroid test) results weekly.
Tomato spotted wilt virus (TSWV) in peanuts and home garden tomatoes
Incidence of TSWV is increasing in the peanut crop. We have the advantage of having a lot of peanut thrips trials evaluating varieties and many insecticide control options where we are also able to rate TSWV severity. Hopefully, we will find the most effective alternatives for minimizing both thrips and the disease. We are also getting reports from home gardeners that tomato plants are showing disease symptoms. When disease symptoms begin to express in a plant, there is essentially nothing that can be done to decrease the severity. Some feel that removing infected tomato plants will prevent, or at least minimize the risk of transmission to other plants. Maybe, but the transmission has to occur from adult thrips that acquired the virus by feeding on infected plants while in the larval stage. An insecticide protection regime designed to control thrips can help a lot in reducing the spread of the virus from plant to plant.
Spider mites in soybean
We diagnosed a very heavy spider mite infestation on a soybean seedling sample from the Northern Neck area but are not hearing of widespread problems…yet. Although some areas got some decent amounts of rainfall over the last weekend, some areas are still pretty dry with conditions very conducive to spider mite outbreaks. If treatments are needed, Dimethoate is likely the best product choice as it has efficacy against adults and immatures, and some systemic activity. But, according to one of the suppliers with Cheminova, it is important to be certain the product is newly manufactured and has been stored properly. If the product is old or has been exposed to extreme high and low temperature fluctuations, it can be ‘denatured’ which greatly reduces its efficacy.
Thrips update, a tough year
We are definitely having a tough thrips year in cotton, somewhat less in peanut. Growers have reported less control than normal with treatments of Orthene/Acephate, even at rates that used to provide good control. Two things may be happening. One is that treatments did kill a lot of thrips but fields are being continually invaded by adults, especially from nearby grain fields that are drying down. Or, earlier treatments killed most of the tobacco thrips and left or ‘encouraged’ outbreaks of western flower thrips that are much less susceptible to Orthene/Acephate. The only way to confirm a western thrips population is to provide our lab with a soapy/jar sample of clipped seedlings. We rinse them from the plants and ID them using a microscope. Without the knowledge of what species are present, it becomes a question of what insecticide to use. We are rating trips trials daily to generate the data to help guide that decision. For example, in one test we made two foliar applications, the first at bud stage and the second in 7 days. As of this week, we had an average of 71 thrips larvae in the 5-plant sample from the untreated control (definitely a lot of pressure). Orthene 97 at 4 oz provided 87% control, Radiant at 6 oz provided 78% control, Vydate C-LV at 17 oz 77% control, Lannate 2.4LV at 12 oz 67% control, and Karate Z at 1.28 oz 8% control. There were two surprises. Dimethoate 4EC at 8 oz provided 95% control, but this is higher than we have ever seen previously with this product and it may be a ‘misread’. And, the new product Benevia 10OD (Cyazypyr) by Dupont, which is not labeled yet, provided 98% control.
Here are a few thoughts based on these data and what we are seeing in fields. First, cotton in many fields is close to being in the 4-5 true leaf stage, on the other side of the thrips pressure period when no further thrips treatments are needed. With the recent rains and warm-hot weather, we will see a lot of growth in the next week. Second, there does not seem to be a ‘silver bullet’ product for thrips control as some may lead you to believe. Orthene/Acephate is still hard to beat, with the exception of this new Benevia which is not labeled, yet. But there is a risk to multiple applications of Orthene. It is tough on beneficial insects and could lead to a much higher risk to flaring mites and aphids….remember that Temik was providing early season suppression of both of these pests. If a second spray is being considered (still seeing damage to the new bud), it might make good sense cost-wise to shift to Dimethoate at 8 oz, which seems to work pretty well and can provide some control of spider mites (is used by soybean growers for spider mite control in DE and MD). The cotton entomologist at Univ of Georgia also recommends Bidrin at 3.2 oz. I have not tested Bidrin, but trust his knowledge.
We will continue to monitor thrips and our many research trials and look forward to sharing our result at our upcoming field tour on June 2.
Corn earworm pyrethroid vial test results–alarming early season results
We have initiated our annual program to assess adult corn earworms (moths) for susceptibility to pyrethroid insecticides. As you may recall, this process has been in place for many years throughout much of the southeast. Adult corn earworms (moths) are captured live and placed individually into small glass vials pretreated with either a pyrethroid insecticide, or untreated as a ‘control’. After 24 hours, vials are inspected to determine the number of dead (susceptible) and alive (resistant) moths. Each year we capture and test as many corn earworm moths as we can manage to track the percent that survive. This survival percentage is at least an indicator of how susceptible corn earworms are to applications of the many pyrethroid insecticide options for growers.
We are already seeing some alarming results. First, our moth captures are very high for this early in the season. As of this week (May 23-27), we have already captured and tested over 200 moths, many more than last year at this time. The largest sample was tested mid week and 25% survived. This is a very high early season survival rate compared with previous years and is not a good way to start the season. We will press to capture and test as many corn earworm moths as we can over the next several weeks. Stay tuned to this VA Ag Pest Advisory for weekly updates.
Poncho/VOTiVO seed treatment registered for cotton
Bayer CropScience announces the registration of Poncho®/VOTiVO” seed treatment for use on cotton. Following are quotes from the release statement. Note that this treatment is not a stand-alone for thrips control, but must be used in conjunction with an additional insecticide (e.g., Aeris, Gaucho, or other).
“To control early season insect pests such as thrips, aphids and others, Poncho/VOTiVO should be paired with additional seed-applied insecticides (Gaucho® or Aeris®) from Bayer CropScience.”
“Poncho/VOTiVO protects against damage from a broad range of nematode species, including reniform and root-knot. It provides a new biological mode of action that introduces revolutionary living-barrier science.”
“Employing a new biological mode of action with a unique bacteria strain that lives and grows with young roots, Poncho/VOTiVO creates a living barrier that grows with and protects early season seedlings and roots,” explained product development manager Louis Holloway. “The result means higher cotton yields through a healthier root system and a more vigorous and uniform crop.”
“According to the Cotton Disease Loss Estimate Committee, nematodes remain a major yield-reducing pest of cotton with more than 500,000 bales of yield potential lost to nematode damage in 2009. Poncho/VOTiVO protects against multiple types of nematodes, making it the perfect partner for Integrated Pest Management (IPM) programs.”
For more information, contact your Bayer CropScience field representative or visit: http://www.bayercropscience.us/products/seed-treatments/poncho-votivo/