It was nearly a white mold wipe out for some producers in 2010. The normal white mold “hits,” turned into full on “runs” in some fields as the temperatures skyrocketed and the rains created a steamy fungal paradise under the peanut canopy.
Could white mold be the primary disease problem in 2011? If it is, it would be the fourth year in a row, as it was the primary disease problems in 2008, 2009 and 2010 in most Southeast states. It is always best to be prepared.
For a pre-season article on white mold, the primary recommendations would be a good rotation program and to plant a variety with resistance to white mold. However, now that planting is almost complete and the early season is at hand, here are five thoughts on white mold for the remainder of the crop year.
1. Use appropriate fungicides.
An effective fungicide program should minimize the spread of white mold in a field. As with peanut varieties, soilborne fungicides have seen a changing of the guard recently with new products such as Proline, which researchers are looking at both in-furrow and early season applications and the season-long impact on the management of white mold. Several other fungicides, including generic tebuconazole, can be used for white mold management.
Consult Peanut Rx to determine your risk for the production factors used. In 2010, outbreaks of white mold were due more to extreme heat than the fungicide programs employed.
2. Timing and placement of fungicides is very important.
The appearance of soilborne disease is related to the soil temperature, the growth of the crop and rainfall or irrigation. Fungicide applications for soilborne disease usually start at approximately 60 days after planting, which is typically when environmental conditions are suitable for disease to occur, given the growth stage of the crop.
However, as in 2010, conditions favored the disease earlier, and, therefore, applications of soilborne fungicides ahead of the 60-day mark would have been a wise option. Watch weather conditions and the crop for signs to spray early.
For placement of the fungicide, reaching the crown and lower limbs of the plant is the key to more effective control. For a good way to do this, see number 3.
3. Improve application coverage by spraying at night.
Several years of research have shown the benefit of soilborne applications made at night. Application of fungicides for white mold at night or in the early morning hours when the leaves are folded allows for better penetration of the canopy so that more of the fungicide reaches the crown of the plant and control of white mold can be significantly improved.
4. Watch the weather and adjust programs as necessary.
Higher temperatures early in the season led to aggressive development of white mold in 2010, which continued through much of the season. Rainfall and irrigation can increase the potential risk and severity of the disease. However, researchers say that even without the moisture, the warmer soil temperatures would lead to more white mold. Watch the weather conditions, particularly temperatures, and be ready to begin a fungicide program if temperatures favor white mold development.
5. It is not possible to achieve 100 percent control.
White mold can likely be found in every peanut field every year. Managing the disease means lessening the potential of the disease becoming a yield-robbing problem. A good soilborne fungicide program may provide at best 70 percent control of the disease and, when conditions are favorable, 50 percent control may be all that can be achieved. Remember to help yourself by using varieties with resistance to white mold and rotating away from peanut for a number of years.
For more information on control of white mold and other diseases in peanut, go to www.ugapeanuts.com and click on 2011 Peanut Update. PG