Peanut News Article for August

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As we move into late August and September keys will be to make sure we stay on a consistent and effective spray program to manage leaf spot, stem rot and Sclerotinia blight. Stem rot will phase out in September as temperatures cool but Sclerotinia could flare in significant amounts. With respect to weed escapes, most of the preharvest intervals have passed, so growers will need to avoid applying most herbicides at this point. It has been a good season for vine growth and a number of people applied Apogee. With the great increase in planting of Bailey, a variety with “extra” vine growth that has a semi-bunch growth habit, these applications should assist growers with harvest. On several occasions in my Peanut Notes series sent to county agents I’ve stated that Apogee can increase yields in two ways. First by helping growers stay on rows if they do not have a guidance system and if vine growth is excessive. Secondly, for growers trying to maximize yield by digging as late as possible, Apogee will hold pods on vines and can reduce pod loss during digging. Much of our work in the past has addressed most issues surrounding use of Apogee. Our current efforts are focused on how the newer varieties respond (Bailey and Sugg in particular.) We also have a set of digging date studies with Apogee and Bailey to document yields over time to get a better handle on how well Apogee improves pod retention. With guidance systems available and challenges in supply of Apogee each year, determining the economic value of Apogee in terms of increasing yield by holding on pods will be important. Apogee continues to be expensive relative to many of our other inputs.

Many before me (in particular Drs. Sullivan, Perry, and Spears) have reminded us of how important the digging decision is with respect to yield and grade. I suspect that as long as we have peanuts we will have this point emphasized. One of the biggest challenges we have is that fewer growers have peanuts and the acreage is quite high for many of these growers. It is a big challenge to get across the crop for normal applications of pesticide and other crop inputs, but this challenge becomes even more difficult when it comes to the logistics of digging, combining, hauling, drying and transporting. Dewayne (Johnson) reminds me each year that we can plant and manage a lot more peanuts during the season than we can dig, harvest, sample, and weigh in a timely manner. While that message is slowly sinking in, it becomes a more critical lesson for growers with a lot at stake in the fall, especially considering that they have a lot more to deal with than just peanuts. Last year when the projected price of peanuts began to creep up in light of major weather issues in the southwest and low yield estimates in the southeast, growers were asking how they could gain a few more pounds per acre. My answer then and continues to be now is that emphasis should be placed on timely digging and harvesting. There is a tendency to dig early for some while others simply get there too late and have already lost some yield. Growers digging early often sacrifice grades as well. Growers digging late will maintain grades simply because there are no immature peanuts coming along to add additional weight to the ones that are mature. Just as a reminder, I’ve provided a table showing the relative difference in maturity of varieties, heat units gained over the past few years as we move into the latter part of the season, and yield and grade response to digging. These data are for Gregory and represent a lot of years of testing, but a similar trend in the data would be noted for other varieties. However, the specific response might vary. For example, the variety CHAMPS tends to shed more quickly, so the downside of waiting until the peanuts reach optimum maturity is that an unforeseen event that keeps you out of the field could spell yield loss from more rapid pod shed than we are showing for Gregory. For a while we thought Bailey would be on the same maturity timing as Gregory r NC-V 11, but it appears to be closer to CHAMPS than these two varieties in terms of being ready. It will be important to keep an eye on these and not let them slip past you.

There continues to be no substitute for assessing maturity 2 or 3 times in the fall using pod mesocarp color as an indicator of when peanuts will be at optimum maturity. Note that I used the phrase “optimum maturity” and not “ready.” The individual farmer has to make the determination of

when peanuts are ready to dig based on maturity, acreage, weather, labor, other crops, and capacity to handle the stress of waiting. Please take advantage of the pod maturity clinics the agents provide in the fall. These clinics can help you schedule digging. We know that our best plans can often be dashed, especially by weather, but getting a feel for when to go where and what fields to begin and end with will be a big help. Dewayne has a great deal of experience and often helps agents with these clinics.

We have updated our profile board this year and hope to have it out there for people to use. Hopefully we have simplified the chart to a degree (one less curve and moved some of the supporting information to one side of the chart.) We also added information on the newer varieties, how heat units can really vary in the fall, and logistics associated with digging and harvesting based on equipment size. The old chart reminded me of NASCAR with the company logos, curves, charts, etc. in a small area. That chart, along you’re your favorite driver’s car, is often so confusing it blends in with the surroundings (maybe that is because the cars are going so fast…I do need reading glasses all the time now.) The green line (“optimum maturity now”) was accurate (in my opinion) but may have been giving people the impression they had more time than they actually had given real world logistical issues. Our new chart has the green curve adjusted “to the left” a little with a little more caution relative to digging later. BUT as always, this chart and other resources does not replace the experience you have with your farm and your operation.

I’ve spent a lot of time in this article on digging because the timing of digging is really important and our Virginia types are less flexible than runners in terms of pod shed, etc. I hope the fall provides just the right amount of rain to finish out crop maturity and doesn’t affect digging and harvesting in a negative way. Good luck!

Average heat unit accumulation per day (DD56) from May 1 through November 1 at Lewiston-Woodville during 2009, 2010, and 2011. 
Dates  Average for the Interval Described 
2009  2010  2011 
May 16 to June 15 17.8 19.1 20.7
June 16 to July 15 20.1 24.5 25.2
July 16 to August 15 22.9 26.3 28.0
August 16 to September 15 18.5 20.9 21.3
September 16 to October 15 11.9 14.4 11.1
October 16 to November 1 7.1 9.3 1.3
Heat units needed to reach optimum pod maturity and the relative difference in days required to reach optimum maturity for Virginia market types.
Variety  Heat units required  Approximate difference in days 
CHAMPS 2550 -5
Bailey 2590 -3
Sugg 2630 -1
NC-V 11 2550 0
Gregory 2650 0
Perry 2720 +5
For example, CHAMPS reaches optimum maturity 5 days earlier than Gregory, while Perry reaches optimum maturity 5 days later than Gregory. The above ranking should be used only when varieties were planted in the same field on the same day and when weather patterns were favorable for normal plant and pod development throughout the season.
Response of the variety Gregory to digging date averaged over 14 trials from 2003-2011. 
Days after emergence  Heat unit accumulation (DD56 Yield (% of maximum)  ELK (%)  TSMK (%)  Fancy (%) 
122 2559 85 50 51 83
129 2674 99 54 55 84
140 2826 100 57 60 84
146 2886 96 58 61 82
154 2944 80 60 62 82

Article first appeared as North Carolina Peanut Note (PNNC-2012-051)