Successful weed and disease management depend upon starting off right. Research has shown that keeping fields weed-free for the first six weeks after planting is critical to successful weed management. Weeds that emerge later than six weeks after planting will not affect yield potential from the standpoint of interfering with water or nutrient uptake. However, weeds that emerge later in the season and go uncontrolled can interfere with fungicide applications and harvest, especially digging and inverting. Protecting foliage from the onset of leaf spot is also critical to maximizing yield potential. Growers can use Peanut Rx as a guide for establishing a disease management program that tailors the number of fungicide applications to the risk of foliar and soil-borne disease in each field. The initial fungicide application should be made no later than 30 days after planting in “high risk” disease fields.
We will see a significant reduction in the Southwest’s peanut acres for 2009. These type years have us searching for ways to further trim production budgets in an effort to finish the season with a positive net return. Developing a crop budget is the first step in determining where reductions are possible. However, do not eliminate or reduce inputs if it will result in a significant impact on yield. Working with crop budgets over the last several years, yield is most often the biggest factor affecting overall returns. For example, elimination of a $10 per-acre input that results in a reduction of 100 pounds per acre will reduce returns by $7 to $10 per acre. Obviously, this would have been a worthwhile input. I encourage growers to look carefully at their budget and review inputs, but don’t cut off your proverbial nose to spite your face.
In summer’s latter half, disease management is a priority. Protecting the plant is essential and will pay dividends in the fall, especially if conditions do not favor timely digging. With a wide range of fungicides, spectrum of disease, implications on resistance management and cost should be part of developing an effective spray program. In the V-C, most growers spray at least five times for leaf spot and stem rot. Sclerotinia blight is a separate issue. We often recommend a chlorothalonil spray first, followed by a regime that controls stem rot and leaf spot, followed by chlorothalonil in September. Whether to spray “one more time” depends on weather conditions and crop maturity. When using the leaf spot advisory, be sure to cover the acreage in a short period of time when disease becomes active. Several varieties have some tolerance to disease, giving more “wiggle room” in spray timeliness. Make sure the most vulnerable varieties have the greatest protection.
There is a lot to accomplish after establishing a good stand of peanuts. Target early season weeds while they are small and easy to control. Secondly, begin a fungicide program 30 to 40 days after planting following the AU Leaf Spot Advisory and do not forget to add boron to prevent hollow-heart in the first couple of fungicide sprays. Finally, pull a pegging zone calcium sample about two to three inches deep in the row to ensure adequate calcium levels for pod fill. Almost all fields have adequate calcium for vegetative growth. However, fields require additional calcium applied to the soil surface if the soil test calcium level is less than 500 pounds per acre to allow the transfer of calcium in the soil solution to the pod through the hull.