Plant diseases can thrive with too much rain

Published 8:53 am Wednesday, July 22, 2015

by Janet Spencer

Recent rains have certainly favored plant growth, unfortunately, they are also favoring plant diseases. There are multiple reports of peanut and corn diseases popping up in several SE VA locations. Not only are we seeing an increase in disease development, but the heavy rains have possibly leached nutrients away from the root zones. The weather forecast was predicting several days with low rain chances, but as of this morning (7/10), the rain chances increased for the next several days. I would never wish for the water to go away, but I do pray your fields are dry enough for you to complete necessary sprays and fertilizer applications.

As always, please don’t hesitate to let me know if I can be of assistance.


Important Dates to Remember:

• Aug. 2: Deadline for County Committee Member nominations. Elections will take place for the

Hardy District (IOW), Blackwater District (Surry), and Chuckatuck/Sleepy Hole District (Suffolk).

• Sept. 30: Deadline to enroll in the ARC/PLC program for 2014 and 2015.

For more information on FSA Programs, please contact:

Glen Pierce (Isle of Wight/Surry): 357-7004

Melanie Lassiter (Suffolk): 539-9265


NRCS has adopted a Soil Health Initiative, which includes no-till and high diversity cover crops among other things to build soil health. Included with this newsletter is a NRCS publication on cover cropping benefits, which you might find useful. If you have any questions about this or other NRCS programs, please contact Mike Faulk, 357-7004 ext. 114.

Rain increases risk of plant diseases

Even though the recent rains are beneficial for plant growth, it also increases the risk of fungal infection to our crops. Peanuts are especially susceptible to diseases following prolong periods of wet warmth. For the most part, peanuts in Isle of Wight are near the R3 (beginning pod) stage and should be sprayed soon for leaf spot. If you are in a 2-3 year crop rotation, leaf spot sprays should begin when the crop has reached the R3 stage, or R4 if you have a longer rotation. Leaf spot sprays for Bailey peanuts can be delayed for 2 weeks after the crop reaches the R3 stage. Currently, we are at a high risk for Sclerotina blight in peanuts. It is strongly encouraged that you begin scouting for signs of this disease and make the necessary fungicide applications if necessary. There are multiple reports of suspected leaf spot in SE VA, as well as at least one confirmed case of Sclerotina blight. Please visit the Cotton/Peanut Infonet for current Sclerotina risk advisories and information on Last Effective Spray Dates (LESD) for leaf spot. The infonet can be accessed at

In addition to peanut diseases, we are seeing corn diseases pop-up in SE VA. Northern corn leaf blight was confirmed on a sample submitted to Dr. Hillary Mehl at the Tidewater AREC’s disease lab. In addition, gray leaf spot has been found on corn in the region. However, before you run out and apply a fungicide, keep in mind there are several factors that a play a role in the profitability of a fungicide application. Corn hybrid susceptibility, yield potential, cropping system, growth stage, disease pressure, and environmental conditions should all be considered when making decisions regarding corn fungicides. A “Corn Disease Scouting and Fungicide Guide” can be found at

One other potential disease issue I want to make you aware of involves the recent confirmation of fungicide resistant isolates of Cercospora sojina, which is the causal agent of frogeye leaf spot in soybean. In 2013 and 2014, soybean samples were collected from four North Carolina and Virginia fields. Of these, two fields contained fungicide resistant strains. So far, resistance is specific to strobilurin (FRAC 11) fungicides. While normally very effective against diseases, resistance can occur very rapidly within this group of fungicides.

When choosing soybean fungicides, pay special attention the FRAC grouping and make sure to rotate sprays with different fungicide groups. This is key in helping to prevent fungicide resistance issues. Dr. [Hillary] Mehl is trying to establish an effective fungicide resistance monitoring program, so if you have fields with symptoms of frogeye leaf spot, we need to submit those samples to the disease lab for testing. Symptoms of frogeye leaf spot begin as small, yellow spots on the leaves. These spots eventually enlarge to a diameter of about ¼ inch. The centers of these lesions become gray to brown and have reddish purple margins.

Pesticide container recycling date set

I’ve had a few growers in the county ask if they can just bring their empty pesticide containers the day VDACS comes to recycle them and the answer is YES! I know many of you dislike having to throw the containers into the storage bin, so if you are interested in bringing them the day we recycle, please let me know. We are tentatively scheduled for either the afternoon of July 27 or the morning of July 28. The first stop that week is Southampton County, so our exact date/time will depend on long it takes with their containers. Please let me know if this of interest to you and how many containers you think you might bring. My plan is to compile a list of interested growers that I can get more information to as we get closer to these dates. VDACS will not return for recycling until the fall and my storage facility can fill up quick, so please take advantage of this opportunity.

Upcoming Events

• VA AG Expo: Aug. 6. Brooke Farms, LLC. Locust Grove, VA (Orange County).

• SE VA Soybean Field Day: Aug. 7, at 9 a.m. Brown Farm, 3320 North Landing Road, Virginia Beach. To RSVP, contact Jill Wright, 385-4769 by Friday, July 31.

• VA/NC Cotton Field Day: Aug. 11. Tidewater AREC (main facility). Contact Gail White for more information at 657-6450, ext. 430, or

JANET SPENCER is the Extension Agent, ANR, for Isle of Wight County. Contact her at 365-6256 or