Cook Extension Ag Updates 10/19/17

Cook County 2017 Peanut Fungicide Trial Results

This is a brief summary of the results from a peanut white mold fungicide trial conducted in Cook County with UGA Peanut Specialists that was just wrapped up .  6 white mold fungicide programs and a control (Bravo Only) were evaluated.  One program (tebuconazole) was compromised and thrown out of this summary. Listed below are the white mold fungicides used – plus the control fungicide (Bravo).  Leaf spot was insignificant in this trial.  White mold pressure was light in this trial (control averaged less than 6% white mold) but was heavy enough to see differences in fungicide programs.  Call me if you want more detailed information or would like to discuss these results 229-507-8862.  Tucker

Pecan Price Report – Lenny Wells UGA Pecan Specialist

With pecan harvest underway, growers should check the current market prices before selling their crop. Prices will be updated each Tuesday and Thursday through the harvest season. Copy and paste this link for prices https://search.ams.usda.gov/mnreports/tv_fv140.txt

Peanut Diplodia Collar Rot

Near peanut picking time, vines will look weathered.  Often you can find late season diseases that push them over the edge just before digging.  If white mold or rhizoctonia limb rot has been ruled out, check the symptoms in the images below. This is “Diplodia Collar Rot” caused by the fungus Lasiodiplodia theobromae.

Here are some points to consider about diplodia Collar Rot from Dr. Kemerait, UGA Peanut Specialist;

1. ” Early season Diplodia Collar Rot  sometimes affects young peanuts much like Aspergillus crown rot.  But this is not common.
2. Diplodia collar rot is commonly seen affecting peanuts later in the season and almost always on peanuts also affected by Tomato spotted wilt.
3. Very very rarely do I find plants affected by Diplodia collar rot and not by TSWV.
4. My thoughts are that the Diplodia pathogen is much less able to infect the peanut plant unless the plant is compromised by something else, especially TSWV.
5. The pattern of the Diplodia collar rot in the field is typically “scattered” (like spotted wilt) rather than “clustered” like white mold, CBR or nematodes.
6. Symptoms of Diplodia collar rot are easy to identify, once you recognize them.
7. In picture attached, note the dark gray-green fungal growth inside the pod.
8. Note individual plants dying in the field.
9. Note the dark, slate gray color of the affected limbs (different than for white mold)
10. MOST IMPORTANT:  note the myriad of tiny, erumpent, black pycnidia on the surface of the gray limbs.  This is a dead giveaway.

NOTE:  Fungicide programs seem ineffective in management of the disease late in the season, likely because of the association with spotted wilt.”

Local UGA Field Trials in Cook County

Local, unbiased, research based data from UGA Extension is hard to beat.  Here are a couple images from two trials in Cook County conducted with UGA Extension Specialists.