Learning to Manage What We Can Control Brandenburg Peanut Notes No. 26 2019

— Written By

Learning to Manage What We Can Control

Rick Brandenburg

Peanut Extension Entomology Specialist

NC State University

Farming has certainly become one of the most complex enterprises anyone could ever want to be a part of. The uncertainty of the weather, the selections, and choices that need to be made prior to the first seed going in the ground, the decisions that need to be made during the growing season and ultimately the conditions at harvest and the markets. The only thing that is truly under our control are the decisions that we make. However, we are often forced to make these decisions under a constantly changing set of circumstances and without all the needed information. One thing is certain. It’s not easy.

While the weather is one thing we have absolutely no control over, there are many other factors that we can completely control and others that we have some control over. We can control the variety we select and we can improve that decision by reviewing what we need most in a variety such as disease resistance. We can control how we manage early-season thrips with our selection of in-furrow treatments ranging from AgLogic to phorate to Admire Pro to Velum Total. Over the years, we’ve had success with all of these products. We can further guarantee success with a foliar application of acephate at 3 weeks post planting. The research that Dr. Jordan and I have conducted for many years consistently indicates a benefit from this postemergence application.

You have some control over planting, but it rarely works out exactly as planned. Too wet or too cold often delays planting, but some minor delays may be OK as it could get you out of the window of highest risk for tomato spotted wilt virus (TSWV). Be sure you review the tomato spotted wilt virus guidelines in the Peanut Information 2019 book (pages 93–96) to understand the role variety, tillage, plant populations, at plant insecticide use AND planting date have on the risk of higher levels of TSWV. While the high levels observed in 2002 and 2003 have not been observed in recent year, this disease is still present. You do have control over how many of these factors you choose relative to reducing your risk from TSWV.

Once we move into mid-season and later it becomes a question of how much time you spend monitoring pest problems. Caterpillars or worms can be an issue from mid-season onwards. This has become more complicated with the presence of bollworms in peanuts and the pyrethroid resistance we observe with corn earworms or bollworms. We use to automatically use a simple spray of a cheaper pyrethroid, but now we are commonly choosing to use a more expensive “worm” insecticide to guarantee results. As a result, we have increased the thresholds to 6 to 8 worms per row foot until September when we bump it up to 8 to 10 early in the month and more than 12 by mid-September. Please review the information in Peanut Information 2019 on pages 81–83 to determine thresholds for treatments and recommended products given the resistance levels and budworm populations in peanuts. Also, keep in mind that staying away from pyrethroids in the middle-to-late season may help reduce the threat of spider mites.

The final insect that requires us to make a decision is the southern corn rootworm. We have been concerned about this pest as long as I can remember and despite investing a lot of time and funding into research on this pest, we really have not been able to improve upon its control nor our decision making. Chlorpyrifos is the only product we currently have labeled for southern corn rootworm control in peanuts, it must be applied preventively (in other words, before the problem begins), and our ability to predict rootworm problems is weak.

We developed a southern corn rootworm risk index many years ago and it is outlined on pages 84–86 and 97–98 of Peanut Information 2019. While it helps us avoid unnecessarily treating fields that are very low risk (sandy soils, early planted or early maturing varieties), most of the peanut fields fit into a “gray area” of not knowing for sure. Over the past 30 plus years I have seen some peanut fields that have been seriously damaged by rootworms, but most of the time the damage I see does not affect yield or quality. Chlorpyrifos also can contribute to spider mite outbreaks, so there is certainly a strong desire to leave it out of the production plan if at all possible. However, rootworms strike fear in the hearts of many especially those who have seen severe damage in heavier soils.

We have nothing new to offer that will aid in this decision-making process. Your own history in each field helps some, but it is almost like flipping a coin. You make the call and you live with the results. Research will continue with some new products that are showing some promise, but their use is still several years away and they don’t get us away from the preventive application. These new products do not appear to encourage spider mite outbreaks, which is a good thing.

So, like every year you’ve ever farmed, you will be making a lot of decisions before, during, and after the growing season. My encouragement for 2019, is that you make it a point to monitor and watch the results of each decision. Record keeping and evaluating the results are the keys to improving your decision-making skills. Good luck with this year’s peanut crop.