Peanut Harvest & Row Crop Disease Update

Boston Peanut

Boston Peanut

Golden Peanut in Meigs

Golden Peanut in Meigs

After afternoon showers and rain last week, we are really getting back to picking this week. Growers are also wide open on defoliating cotton. I saw some cotton being picked yesterday.

I visited our buying points this week and looked at grades and other issues. Thankfully, we are not having many Seg 2 burrower bug hits as last year and the year before. Between both buying points, I only know of one known burrowing bug Seg 2. In every other Seg 2 case, they’ve turned around and cleaned them and they were fine.

Grades are probably a little down this year compared to last, but are definitely not bad. Many good grades overall and low percentage of our sound splits and other kernels (pops). We could be pulling the trigger early on the some of the fields. Almost all growers are checking maturity twice in fields before digging, and many have checked more than two times. We’ve not seen maturity develop at a normal pace with our dryland peanuts which has made digging decisions tough. With more peanuts in the ground, growers are having to dig when they have help, or wagons are available, or weather permits. Vine condition is also a factor in our decision at this time. Overall, we’ve had good harvest conditions this week. Even with afternoon storms or showers, sunny days have been able to dry peanuts quickly.

Collecting grading samples at Boston Peanut

Collecting grading samples at Boston Peanut

UGA Extension Pathologist Dr. Bob Kemerait has this information on current disease issues:

Peanuts

Harvest is well under way by this time, but disease issues still affect peanuts that won’t be harvested for another three weeks or more. I have seen some fields where harvest is approaching and where white mold (stem rot) is still active, and I have recommended growers late in the season apply a mixture of tebuconazole and chlorothalonil to finish the season (both products have a 14-day preharvest interval). Other white mold products could also be applied (check preharvest interval first), but with time running out in the season, the value of tebuconazole is certainly a consideration.

Late Leafspot

Late Leaf Spot

I have also observed where leaf spot, especially late leaf spot, is aggressive late in the season, primarily on a susceptible variety like ‘Georgia-13M’. If less than two weeks to go before digging, it is doubtful anything should be applied (or legally can be applied). If peanuts are 30 days or more away from harvest, then the grower can mix a pint of chlorothalonil with 5.5 fl oz/A of Alto. If harvest is more than 14 days away from harvest, the grower can mix 5-10 fl oz/A Topsin with a pint of chlorothalonil. Fields where defoliation from leaf spot diseases has reached 50% or more and have not yet reached the optimal digging date should be considered for an early digging.

Soybeans

Soybean producers in southern Georgia have experienced losses to Asian soybean rust this year; however it appears that most have successfully protected their crop with judicious fungicide applications. MORE IMPORTANTLY, I have observed a SIGNIFICANT amount of frogeye leaf spot (Cercpospora sojina) disease in a number of fields this year; something I have not seen in many years. I am not sure why this is so; however it is something we will need to watch again next season as well. Additionally, I am seeing pre-mature defoliation to Cercospora blight (Cercospora kikuchii) in a number of fields; this disease often results in purple stain of the soybean seed. Cercospora blight is diagnosed, in part, by the prominent loss of leaves in the top of the plant leaving only the petioles, reaching like bony fingers to the sky.

Cotton

Bacterial blight (Xanthomonas citrii pv malvacearum) continues to cause concern to many growers in the state. From your reports, reports from our consultants, and from my own observations, it is clear that bacterial blight can be found in a number of fields across the Coastal Plain. Classic symptoms or bacterial blight on leaves, bracts, bolls, stems and petioles are fairly easy to diagnose; still symptoms of other diseases may inadvertently be diagnosed as “bacterial blight”. 

It is my belief, based upon my observations and discussions with a number of experienced individuals, that losses to this disease are likely to be small and even negligible in many fields. Finding a little bit of disease in a field is an important contribution to understanding the occurrence of bacterial blight in 2016; but incidence alone does not mean significant yield loss.

Certainly there are some fields, especially in extreme SW Georgia, were boll rots appear to be closely associated with bacterial blight and losses are likely to occur. Effective management of bacterial blight by a grower revolves around variety selection (we are composing such a list for Georgia cotton producers now) and management of crop debris/residue as the pathogen can overwinter in such. Crop rotation and burying of crop debris can help to minimize the development and spread of the disease in upcoming seasons.

Bacterial Blight

Bacterial Blight

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