Peanut Update
W. Scott Monfort
Extension Peanut Agronomist, UGA
The 2017 harvest is slowly getting under way. A few thousand acres have been inverted and are now being harvested. Thus far, maturity is bouncing around from 135 to 150 days after planting. There are several key factors that might be contributing to this variability. Last year’s harvest season was extremely dry and warm causing the germ and vigor (mostly vigor) to be reduced for the 2017 seed stock. The reduced vigor caused the plants to grow slower than normal increasing issues with Valor injury and crown rot. These issues coupled with this year’s weather are the primary culprits for the maturity inconsistencies observed so far. Some of the other maturity issues I am seeing around are due to the mid-to-late August drought conditions we experienced throughout the state. The dry conditions caused many acres to completely stop in their tracks at around 110 to 120 days old. These fields need to be checked and dug as needed. The good news is the irrigated crop seems to be above average. The profile of many of the irrigated fields look excellent with very few pops or damaged kernels.
What about the Elephant in the room (Hurricane Irma)? What do I need to do? The good news for a majority of the crop is that we are still early in the harvest season and should fair the storm okay. This does not mean we will not observe some damage or loss. The acres I am most concerned about are the ones showing signs of vine collapse due to disease, week or poor peg strength, and non-irrigated fields that have stopped and are now coming loose in the hull. These fields need to be examined and potentially dug before the storm reaches Georgia. The fields that are nearing maturity but have good vine and peg strength will do better in the ground than above ground. I would suggest you look at each field individually when making harvest recommendations to your growers. Please feel free to call me if you have any questions or need to discuss a specific situation.
Points to Consider for Late-Season Disease Control in Peanuts
Robert Kemerait
Professor and Extension Specialist, Department of Plant Pathology
University of Georgia
Late-season disease recommendations for a peanut crop are often confusing. Reasons for this include A) digging/harvest dates are not “set in stone”, B) the incidence of one disease versus another affects choice of fungicides, C) disease can be cryptic, as in the case of underground white mold, and D) there are a number of fungicide options that can be deployed. Therefore, it is increasingly important that growers can get guidance from UGA Extension as they make their decisions. While there may not be a single “best” recommendation, some solutions are better than others.
The possibility that Hurricane Irma could affect our harvest season makes late season disease management options even more important. If, as the path of Irma becomes more evident, it seems that the hurricane could delay our peanut harvest, then it becomes more critical to protect the crop before the storm hits.
Growers often request advice on adjusting digging dates based upon disease in the field. Generally, it is best to wait until harvest maturity is reached in order to assure maximum grade, rather than digging the peanuts early. For example, though tomato spotted wilt may be severe in a field, I recommend waiting until harvest maturity to dig the peanuts. However, where defoliation from leaf spot is severe, then it is worth considering digging earlier. Where white mold is severe, for example greater than 50% incidence, the grower should consider if digging early is appropriate. Significant defoliation from leaf spot diseases and severe outbreaks of white mold can increase digging losses by weakening peg-strength.
NOTE: A critical consideration late in the season is that pre-harvest intervals (PHI) vary with the choice of fungicides. For example, Alto has a 30-day PHI, and Convoy has a 40-day PHI, compared to 14-day PHI for other fungicides. Growers must always check the label to make sure on all of these.
Below are some typical situations that peanut growers may find themselves in and suggestions for control:
• Grower is 4 or more weeks away from harvest and currently has excellent disease control.
o Suggestion – I recommend the grower apply at least one more fungicide at least for leaf spot control.
o Suggestion – Given the low cost of tebuconazole, the grower may consider applying a tank-mix of tebuconazole + chlorothalonil for added insurance of white mold and leaf spot.
o NOTE 1: If white mold is not an issue, then the grower should stick with a leaf spot spray only.
o Note 2: If grower has planted Georgia-06G or Georgia-12Y and the plants are leaf spot-free at 4 weeks prior to the anticipated digging date, an additional fungicide application for leaf spot may not be needed if grower is willing to watch/scout the field for other disease, for example peanut rust.
• Grower is 4 or more weeks away from harvest and has disease problems in the field.
o If the problem is with leaf spot – Grower should insure that any fungicide applied has systemic/curative activity. If a grower wants to use chlorothalonil, then they would mix a product like thiophanate methyl (Topsin M) or cyproconazole (Alto), with the chlorothalonil. Others may consider applying Priaxor, if they have not already applied Priaxor twice earlier in the season.
o If the problem is white mold – Grower should continue with fungicide applications for management of white mold. If they have completed their regular white mold program, then they should extend the program, perhaps with a tebuconazole/chlorothalonil mix. If the grower is unhappy with the level of control from their fungicide program, then we can offer alternative fungicides to apply.
o If the problem is underground white mold – Underground white mold is difficult to control. Applying a white mold fungicide ahead of irrigation or rain, or applying at night, can help to increase management of this disease.
• Grower is 3 or less weeks away from projected harvest and does not currently have a disease issue.
o Good news! This grower should be good-to-go for the remainder of the season and no more fungicides are required. SEE NOTE BELOW ABOUT HURRICANES
• Grower is 3 or less weeks away from harvest and has a problem with disease.
o If leaf spot is a problem and 2-3 weeks away from harvest, a last leaf spot fungicide application may be beneficial. If leaf spot is too severe, then a last application will not help. Tank mixing chlorothalonil with a systemic fungicide, like thiophanate methyl or other appropriate systemic fungicide, could be beneficial.
o If white mold is a problem and harvest is 3 weeks away, then it is likely beneficial to apply a final white mold fungicide. If harvest is 2 weeks or less away, then it is unlikely that a fungicide will be of any benefit.
o NOTE: If harvest is likely to be delayed by threat from a hurricane or tropical storm, then the grower may reconsider recommendations for end-of-season fungicide applications.
Hurricane Irma and Pecans – Lenny Wells
After a blog post about the approach of one of the Tropical Storms that came through Georgia last year, a friend of mine said to me, “You couldn’t offer them any advice except to turn the water off?” Well, we are facing a more serious wind event now with Hurricane Irma and unfortunately that’s really all we can do so my advice remains the same. Turn off the water for a few days until the storm passes. Our crop looks good right now and we don’t need a storm like this to pass through at this point. I’ve seen many heavily loaded trees that don’t need any wind at all.
Shuck split is progressing well on Pawnee and we could see harvest begin on this variety within another week or two. For our major varieties, the nuts I cut by the end of last week and through the weekend were pretty well filled out so kernel filling is almost complete. This is another indication our crop maturity is a week to 10 days ahead of schedule. We would normally continue irrigating at 100% until mid September but with the storm approaching, turn the irrigation off and allow the soils to hopefully stiffen up somewhat before any wind may arrive. It looks like we are set up for several days of clear, dry weather prior to the storm’s arrival and it would be better to sacrifice a little nut quality than to lose trees.