Category Archives: Commodity

Worms in Sorghum

Posted on August 28, 2014 by Ames Herbert

We received a sorghum head sample today from Dinwiddie County with sorghum webworm (see image on right). This is a known pest of sorghum and we have seen them before, but because of their smaller size compared to other head worm species, the threshold is an average of 5 per head across the field. To date, we have never seen nearly this many in any field, but this is a pest that should be scouted for. We are also seeing a very large number of fall armyworm moths in our pheromone traps here at the Tidewater Center. Fall armyworm is another sorghum head pest (see the image below), along with corn earworm, and the threshold for these species is an average of 2 per head. We recommend scouting sorghum fields until heads have hardened seeds. If fall armyworm is found in threshold numbers and a treatment is needed, pyrethroids will not do the job. The best results will be with non-pyrethroids like Belt, Prevathon or Besiege.

Brown marmorated stink bug (BMSB) and kudzu bug (KB) in more counties but numbers still very low

Posted on August 28, 2014 by Ames Herbert

We are still finding BMSB and KB in new places—7 new counties for BMSB (Sussex, Albemarle, Cumberland, New Kent, King George, Isle of Wight, and Surry), and KB in 3 new counties (Mathews, Mecklenburg, and Virginia Beach)—but numbers in all locations are way down compared with last year (see the maps below). No fields are at threshold for either pest, but a couple of fields were identified in James City County that have some infested edges. The full season crop is going to be safe from injury soon, when plants grow through the R6 stage. As the season moves into late summer and early fall, double crop fields will provide one of the few good late season food sources for all stink bug species—so they will need to scouted until they are safe from injury.

Mysterious leaf spots in peanut

Posted on August 28, 2014 by Maria Balota

In the past two weeks or so, there were discussions among specialists about peanuts showing a “mysterious leaf spot” of non-pathogenic origin (credit to pathologists Barbara Shew and Hillary Mehl); but the spot is similar in appearance to the early leaf spot when it starts and becomes irregular at later stages.

“Mysterious” leaf spot found in Suffolk, VA. At the initial stage, the spot looks like early leaf spot, but it has non-pathogenic origin.

Dr. Jay Chapin with Clemson University thinks it is a physiological leaf spot; he calls it “irregular leaf spot”. He observed it to be more prevalent on runners, in particular GA09B, and resulting in yield reduction under certain circumstances. Dr. David Jordan calls it “peculiar leaf spot”. I also found it in research peanut fields in Suffolk and Southampton, VA; the spotting was under 25% of the total leaf area. To solve the “mystery” and get information on the frequency of this issue in NC, Dr. Jordan recently launched a survey and asked the Extension Agents to assess the presence and severity of the spot in approximately 20 fields in each county (4 to 5 areas in each field) using the table below. Because I also found the spot in several fields and I know of growers growing GA09B this year, I suggest we do the same in Virginia. Please use the table below; under “comments” please include information on the cultural practices used in each field, if possible, so we can better explain the cause of the spotting. This assessment can be used at winter meetings and presented at the APRES next year together with the NC Extension Agents.

Documentation of Leaf Spots in Peanut that is not early or late leaf spot or web blotch


Field ID (your designation)	Spots present (yes/no)	Severity (none, low = 25% or less leaflets with spots, moderate = 25 to 50% leaflets with spots, high = 50 to 75% leaflets with spots, very high = 75 to 100% leaflets with spots) relative to entire peanut canopy	Comments

Late Blight Found in Montgomery County

Posted on August 21, 2014 by Elizabeth Bush

Late blight has been confirmed on tomato in Montgomery County, VA, by the Virginia Tech Plant Disease Clinic. Potato and tomato growers should take precautionary actions and increase scouting. Cool and wet conditions favor development of this disease and fungicide sprays should be in place before the disease is present in a field or garden. For more information on late blight and late blight management, refer to the Extension publication available at: http://pubs.ext.vt.edu/ANR/ANR-6/ANR-6_pdf.pdf . Late blight was previously identified in Loudoun County, VA, on July 22 and Rappahannock County, VA, on August 8.

Brown marmorated stink bug distribution in Virginia–August 21, 2014 report

Posted on August 21, 2014 by Sean Malone

BMSB was found in soybean in nine new Virginia counties this past week: James City, Caroline, Stafford, Culpeper, Fauquier, Nelson, Rockbridge, Henry, and Montgomery. The highest numbers of BMSB occurred in a Warren field (5 nymphs and 4 adults per 2-minute visual inspection), followed by Augusta (5 nymphs and 1 adult per 2-minute visual), Fauquier (5 nymphs), Buckingham (4 nymphs), James City (3 nymphs, 1 adult), and Appomattox (3 nymphs, 1 adult). Thanks to our soybean scouts and to Dr. Tom Kuhar for their updates this week.

Kudzu bug distribution in Virginia–August 21, 2014 report

Posted on August 21, 2014 by Sean Malone

Our soybean scouts detected kudzu bug in two new Virginia counties this past week (Halifax and Greene); both of these locations had low numbers. The highest numbers of kudzu bugs reported by our scouts for the past week were in a Pittsylvania soybean field (8 nymphs and 3 adults per 15 sweeps), followed by Goochland (4 adults per 15 sweeps) and Henry (3 nymphs and 2 adults per 15 sweeps). Additionally, VCE Agent Scott Reiter reported high numbers of kudzu bug adults along the edge in a Prince George soybean field that was bordered by kudzu (50 adults in 15 sweeps in the first 30 feet of field, diminishing to 3-4 adults per 15 sweeps at 100 feet from the field edge). Scott found other fields with 0-3 kudzu bugs in 15 sweeps.

Peanut Disease Update – August 14, 2014

Posted on August 14, 2014 by Hillary Mehl

Sclerotinia blight risk has been, and continues to be, high this summer and timely fungicide applications based on advisories (Peanut-Cotton Infonet, http://webipm.ento.vt.edu/cgi-bin/infonet1.cgi) and scouting are needed to avoid devastating outbreaks of this disease. Unfortunately, it has been reported that Omega, the most effective fungicide for Sclerotinia blight control, is in short supply, and growers are looking for alternatives. At this point we are recommending Fontelis at a rate of 1.5 pints per acre. According to Barbara Shew, Extension Plant Pathologist at North Carolina State University, 1.5 pints per acre of Fontelis provide Sclerotinia control similar to one pint of Omega. Note that lower rates of Fontelis typically used for leaf spot control are not adequate for control of Sclerotinia. A follow-up Fontelis application should be made 2 to 3 weeks after the first application or according to the Sclerotinia blight advisory, but keep in mind that only two applications of this fungicide class (SDHI, group 7) should be made per year to minimize the risk of fungicide resistance. In fields with high Sclerotinia pressure, avoid using chlorothalonil (Bravo and generics) in August or early September for leaf spot control since this can increase the severity of Sclerotinia blight outbreaks. Alternatively, use strobilurin fungicides such as Abound or Headline or a triazole such as Provost for leaf spot control. However, the final leaf spot application of the season should be chlorothalonil for the purpose of fungicide resistance management.

Southern Rust in Corn – Update

Posted on August 14, 2014 by Hillary Mehl

Southern rust continues to be reported on corn in Virginia. Southern rust was first confirmed August 3 on corn samples from Chesapeake and Suffolk. Since then, reports of southern rust have been made from Sussex and Albermarle counties, and it is likely that the pathogen is throughout much of the state. Yield of corn at or near the dent stage is unlikely to be impacted by the disease, but late planted corn in fields with good yield potential (120 bu/ac +) may need to be protected with a foliar fungicide. Strobilurins are good preventative fungicides whereas triazoles are recommended once sporulation is observed in a field due to their curative activity. A combination fungicide is a good option as long as a strobilurin fungicide has not been applied previously. Wet, warm weather favors disease development. Once sporulation occurs, symptoms of rust are relatively obvious. Lesions start out as raised, blister-like pustules then break open to reveal orange spores. Samples of corn plants with symptoms of southern rust can be submitted to the disease clinic at the Virginia Tech Tidewater AREC (contact Dr. Hillary Mehl, hlmehl@vt.edu).

Black light trap catches for the week ending August 14, 2014

Posted on August 14, 2014 by Sean Malone

Corn earworm moth catches are increasing; please click on “BLT_14_Aug_2014” below for your local trap catches of this insect and also the brown marmorated stink bug. Thanks to the following for their reports this week: David Moore, Keith Balderson, Watson Lawrence, Kelvin Wells, Mark Kraemer, Chris Drake, Mary Beahm, Mike Parrish, Janet Spencer, and Ames Herbert and his entomology team.

BLT_14_Aug_2014

Update on kudzu bug and brown marmorated stink bug

Posted on August 14, 2014 by Ames Herbert

We are providing updated maps of the distribution of kudzu bug and brown marmorated stink bug in Virginia. Although we have added a few new counties since last week, overall the populations of both of these pests are very low compared with last year. To our knowledge, no soybean fields have even come close to reaching threatening levels or thresholds.

Most kudzu bug egg masses that we are finding have already hatched indicating that the second generation is occurring. This pest has only two generations so if this second generation stays small, as it appears, we may not have to treat any fields this year.

Brown marmorated stink bug levels are very low. Although a few can be found in many fields, none are reaching high levels. All of this is good news for growers. But, the season is far from over so stay vigilant.