Category Archives: Commodity

Now is a Good Time to Evaluate Your Varieties for Foliar Diseases

Posted on September 11, 2014 by David Holshouser

September is a great time to evaluate your crop and the performance of varieties that you chose. In addition to general growth and health of the crop, take some time to determine if you have any of the below diseases. If so, you could be losing some yield. If you sprayed with a fungicide and still have disease, reconsider the product and rate used and the time that the fungicide was applied. Keep in mind the weather conditions when the application was made and the conditions 2 to 3 weeks after or before the product was applied. Cool temperatures (70’s) and high relative humidity (>95% for 12 hours or more) will usually increase disease incidence.

Another caution is to never diagnose a specific disease on the plant without verifying it with a person trained to identify plant pathogens. Only when the reproductive structures are found on the leaf can a disease be confirmed. Many things will cause look-alike symptoms. Be sure before you cast the blame. There are more diseases than just the ones shown below, but these are the most common. Brown spot is normally found in the lower part of the crop canopy (the lower leaves), Cercospora blight and leaf spot will be found throughout the canopy, and the frogeye leaf spot and downy mildew tend to be found in the upper part of the canopy.

BMSB and Kudzu Bug Update, Sept. 4, 2014

Posted on September 4, 2014 by Ames Herbert

Although numbers are still generally very low, our field scouts and others have found BMSB and kudzu bug in a few new counties this past week. The eight new counties added for BMSB are Gloucester, Charles City, Hanover, Spotsylvania, Rappahannock, Prince George, Suffolk and Chesapeake (thanks Stan Winslow for the Chesapeake report). The two new kudzu bug counties are James City and King William (thanks Paul Bodenstine for the King William report). See the maps below for the most recent distributions. Although there may have been a few fields treated for these pests, as far as I can determine most have not. We know of one grower in Campbell County who had some threshold numbers but only in a few patches along one field edge. He elected to spot treat only these patches and so far, our post treatment visits have shown that this strategy was successful, that is, no reinfestation and no spread.

Peanut Crop Update for Virginia

Posted on September 3, 2014 by Maria Balota

Maturity wise, seasonal heat units accumulated by peanut fields from May 1^st to Sep 1^st in Virginia are between 2252 to 2376 °F. Therefore, we started a weekly pod maturity determination by the pod mesocarp color of Williams and Drexler (1981). We grouped the pods on a maturity board into white, yellow, orange, brown, and black color groups. The profile maturity classes defines white and yellow as immature, and orange, brown and black as mature pods; orange is defined as incipient maturity, brown full maturity, and black over mature pods. We used Bailey planted on May 5^th and May 20^th, and CHAMPS planted on May 27. Both Bailey and CHAMPS mature in approximately 145 days after planting or 2600 heat units. Peanut maturity determined on Sep 2nd

Our data indicate that in Virginia all plantings have the majority of the pods, 75 % to 91%, in the yellow and orange color groups (yellow predominates) with more spread for early May plantings (12% were in the white and 13% the brown group) and more uniform pods for late May planting (only 9% were a combination of white and brown).

Appearance wise, peanut vines start showing drought symptoms due to current high temperatures and absence of rainfall in many fields in Virginia. As of now, we are looking at 30 to 40 days to optimum maturity but more delay is expected if no significant rainfall will be soon received and in absence of irrigation.

Late Blight Found in Floyd County

Posted on September 1, 2014 by Elizabeth Bush

Late blight has been confirmed on tomato in Floyd 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; Rappahannock County, VA, on August 8; and Montgomery County, VA on August 20.

Corn earworm update: few moths but with high tolerance to pyrethroids

Posted on August 28, 2014 by Ames Herbert

Although we hear rumors of worms in soybean fields, our scouting does not confirm this. We are finding almost none in either full season or double crop fields—and others are reporting the same. The full season crop is quickly approaching the ‘safe’ zone, that is, the point where pods are too tough to be attractive to insect pests. But, the summer is not over yet. Because corn is slow to dry down this year, we may still see a corn earworm moth flight into soybean fields, and if this happens, double crop fields would be a primary target. This is also true for stink bugs. As we get into late summer and early fall, stink bugs will be attracted to double crop fields. We strongly recommend that you begin checking double crop fields.

Because of the very weak corn earworm moth flight, we have not been able to capture and test nearly as many moths for pyrethroid tolerance as we have in the past. But all indications are that levels are high (see the graph below). In the most recent sample more than 40% survived the vial challenge. If this high pyrethroid tolerance level coincided with a large flight the large numbers of worms in fields, we would no question be recommending non-pyrethroids. But with this weak flight and the low numbers of worms in fields, I think we can get decent enough control with high rates of pyrethroids, alone.

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.