Peanut Pointers: July 2023

Scout Weekly To Adjust Plans Depending On Moisture Level

emi kimura
EMI KIMURA
Texas A&M AgriLife Extension
State Extension Peanut Specialist

We have received good precipitation through May, which has reduced drought intensity in the Southwest. However, the West Texas region remains under drought conditions. This region has received only an inch and a half of rain since the beginning of 2023. 

While temperatures have been milder than they were in 2022, more rainfall is needed to maintain good soil moisture for the optimum development of peanuts. Depending on the amount of precipitation and humidity levels, production plans may need to be adjusted accordingly. 

The higher the precipitation and humidity levels, the more pest issues are expected. Although many of our growers are using preventative fungicide programs, weekly scouting is needed to adjust these plans as necessary.

Growers in areas with high precipitation need to carefully monitor weed infestations, and treat them accordingly. It is important to scout fields, especially as the crop transitions to flowering and pegging, where yield potential can be greatly affected by the biotic and abiotic stress factors. 

Rainfall Is Not Always The Best Indicator Of Leaf Spot

DAVID JORDAN
North Carolina State University
Extension Agronomist

Our primary focus in July is establishing and maintaining an effective fungicide program for leaf spot and stem rot. In North Carolina, we recommend that the first spray be made at the R3 stage of peanut growth but no later than July 10. We typically have a five-spray program in our area when considering two-week intervals. If you have a shorter rotation that may have more disease inoculum, starting the program a week or so earlier will minimize risk. 

It is recommended that you start with a chlorothalonil treatment either alone or with a tankmix partner that has some curative activity. If you are closer to mid-July with your start, then a fungicide treatment that also has stem rot activity is recommended. Sprays three, four and five (if you start in early July) will need both leaf spot and stem rot fungicides. Numerous combinations are effective on pathogens that cause these diseases. 

The key is to stay on a two-week interval for many of the fungicides you might apply, and rotate chemistry for resistance management. Some fungicides will provide control longer than two weeks. 

The final spray should include chlorothalonil. In some years, and depending on when you started your spray program, a sixth spray may be needed, especially if September is warm and peanuts are not going to be dug until sometime in October.

We have seen less and less Sclerotinia blight over the past decade, but it is still out there. Resistance in our Virginia-market type varieties (Bailey II and Sullivan) is good for this disease. The exception is Emery, but it is much better than the older varieties like CHAMPS and Perry. Depending on the fungicides you are using for leaf spot, you may also be controlling any Sclerotinia blight you might have with those products. 

If we get dry during July and August, keep in mind that rainfall is not always the best indicator of whether leaf spot will continue developing. We have observed significant leaf spot under drought — defined by no rain — if dew points are high at night. The leaf spot advisory can help you keep spraying when risk is high and stop spraying when the risk is low.

Our current thresholds for foliar-feeding insects, such as fall armyworm, corn earworm and tobacco budworm, are relatively high. However, if you need to make an application, use caution, especially if it is dry and spider mites are building. If you use a pyrethroid, it is very likely mites will become more prevalent. Other insecticides, although more expensive, can minimize the risk of spider mites and are more effective on pyrethroid-resistant individuals in the population.

If it turns out we have good growing conditions, Bailey II and Emery, and in some cases Sullivan, can have excessive vine growth. Apogee or Kudos can help a lot here. The first spray goes out when 50% of vines from adjacent rows are touching. A second application can be made two to three weeks later, if needed. Do not force the second spray. You will begin seeing regrowth and that is the time to make the follow-up application. We can set peanuts back if we apply these plant growth regulators under dry conditions or if we start the sprays too early. Always include nitrogen with these PGRs. There are many questions in July and August about tankmixing, but there is not nearly enough room to address those questions here. 

No Simple Solution To Getting The Crop On Track

Scott Monfort
SCOTT MONFORT
University of Georgia
Extension Agronomist

The planting season has been a little crazy with the cool weather and seed quality issues, mostly seed vigor. The good news is that a majority of the crop is up and looking good so far. There are several items to note with the crop at this point. 

One, several fields had a tough time reaching adequate stands because of low-seed vigor and cool, wet weather. In the first part of May, weather caused most of the issues, but as we moved into late May, poor seed quality (seed vigor) became more evident. 

Two, the cool weather also slowed growth and delayed blooming across most of Georgia. 

Three, the cool wet weather also delayed planting by one to two weeks, causing a majority of field plantings to be in mid-to-late May with about 15% to 20% in June. Keep these delays in mind as we go through the season as maturity will be impacted. Also, remember that the yield potential of peanuts planted in June will be reduced 10% to 15% depending on the weather in September and October. June-planted peanuts will need a very warm fall to maximize yield potential. 

One way you can keep up with heat units is through the UGA weather network at www.weather.uga.edu. Click on “Calculator,” and then “Heating Degree Day.”

Talk at the coffee shop lately is how can we push the crop to get back on track. I wish there was a simple solution to get the crop moving to limit potential yield loss. The most important thing for the crop in July is warmer temperatures with weekly rainfall/irrigation. 

Outside of having great weather, yield potential will be dependent on managing key weed, disease and insect issues by using the most effective pesticide and being timely with herbicide and fungicide applications. Growers do not need to forget boron and calcium. 

To make sure plants and pods are growing in the right direction, growers need to make sure to apply calcium if soil levels are below 500 pounds per acre (gypsum 750 to 1,000 pounds per acre) prior to blooming. Apply boron at 0.25 pounds per acre twice at 30 and 45 days after planting. Applying the wrong type of product or rate will not offer productive results. Please give your county agricultural agent a call if you need more information or have an issue you need help with.

Heat And Rain May Warrant Earlier Soilborne Fungicides

Kris Balkcom
KRIS BALKCOM
Auburn University
Extension Specialist

Hopefully everyone has received adequate rainfall over the past month. I know our weather has been unusual this season with May seeming like April and June more like May because of the drier weather. This has created some challenges, mainly getting the crop in on time and having a good stand due to too little moisture or too much, coupled with a packing rain. These later peanuts that went in or that were replanted still have adequate time to reach maturity. All in all, peanuts are looking decent right now. Considering the planting season, we were not able to take advantage of early planting, which sometimes puts us in a tough spot depending on what kind of moisture we have later. 

We have some weed issues to be addressed here and there but nothing too big. Hopefully you have cleaned those up and have some more residual protection down now. 

Remember, even though disease pressure has been light so far, it doesn’t mean that will continue to be the case. I want to remind everyone of the importance of scouting peanuts to be aware of pests, whether it is insects or diseases. Some of us tend to relax and not scout like we should. July is when most growers start to apply their soilborne disease fungicides, which happens to be when the peanuts are typically around 60 days of age. Be mindful of the weather conditions that we have this summer and of the late crop. We very well may need to start earlier, at 35 to 40 days after planting, with the soilborne disease materials if we endure a lot of heat coupled with moisture. 

I hope everyone has a great rest of the season this year, and I look forward to seeing you in the field. PG

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