By Dr. Bob Kemerait, Extension Plant Pathologist
“Though still approximately 6 weeks away from the general start of the planting season, there are issues regarding management of diseases and nematodes affecting peanut that deserve attention now.
Choosing the right variety. Most of our acreage will be planted in ‘Georgia-06G’ and this continues to be an excellent variety. I recognize that seed for ‘Georgia-12Y’ is generally unavailable; however I encourage growers who are concerned about white mold to plant some if they can. Likewise, growers with root-knot nematode problems are encouraged to consider planting at least some of their acreage in ‘Tifguard’ or ‘Georgia-14N’, remembering that Georgia-14N is a later-maturing variety. Growers are encouraged to consult the 2016 version of ‘Peanut Rx’ to determine the predicted risk to tomato spotted wilt, white mold and leaf spot diseases given the variety they plant and their production practices. With this information they can make a better informed decision on their disease management program.
Decisions regarding nematode control are critical now. Growers who anticipate a problem with peanut root-knot nematodes and who plan to apply a nematicide will likely use Telone II or Velum Total. The primary consideration in choosing between a resistant variety, Telone II and Velum Total is the population of nematodes in a field. The economic threshold number, that “magic” number that draws the line between when damage from the nematodes is worth treating and when it is not is “10/100cc soil”. Velum Total (18 fl oz/A) is generally recommended where a grower would have used Temik 15G, 10 lb/A at-plant, which would coincide with “low-to-moderate” nematode populations. Defining “low-to-moderate” populations is unsettling, but I would say anywhere from 10-100 root-knot nematodes per 100cc soil in a FALL-collected sample would be “in the ballpark”. As numbers increase beyond 100/100cc soil, I think a resistant variety or Telone II becomes increasingly important. Also, given that the root-knot nematodes are generally “clumped” in a field, it is likely that even a field described as “low-to-moderate” will have significant “hot spots” in it. Telone II should be applied in-row at 4.5 gal/A in-row 10-14 days ahead of planting with special awareness of soil conditions during this El Niño season. The possibility of frequent rain events could make fumigation challenging. An insecticide for management of thrips is still required when Telone is used but not when Velum Total is applied. Velum Total should be applied at 18 fl oz/A for peanuts and the product can be mixed with other fungicides and inoculants without concern. Whether choosing Telone II or Velum Total, accurate calibration and precise application are critical for maximum success. Growers should ensure that equipment is properly put together and tested for calibration.
By now, most growers are aware that Tilt-Bravo will be generally unavailable this season and the issues concerning sale of peanuts treated with propiconazole (the active ingredient in Tilt) to the European market could affect other products as well. For example, it is not clear how Artisan, a combination of flutolanil and propiconazole will sold this season; however Convoy (flutolanil alone) will be in ready supply. Syngenta will likely recommend a tank-mix of Bravo and Alto to replace Tilt-Bravo; products like Priaxor will also perform well in this early-season spot. As we move beyond planting, additional discussion regarding leaf spot management will be proposed.
White mold is of special concern this year, both because of anticipated short-rotations and because of the severe outbreak we had last year. Growers are reminded that early-season applications of Proline and, perhaps, Elatus can help to manage this important disease. Banded applications are typically made approximately 3-5 weeks after planting. NO FUNGICIDE PROGRAM CAN MAKE UP FOR SHORT ROTATIONS. However using the right products at the right time sure can help