TSWV in 2019 Brandenburg Peanut Notes No. 37 2019
Don’t forget about tomato spotted wilt virus in 2019
Back in 2001, 2002, and 2003, the topic of Tomato Spotted Wilt Virus (TSWV) was on everyone’s mind. The level of occurrence in peanut fields was quite high especially in Georgia, Alabama, and Florida, but it was certainly a problem in North Carolina as well. Fortunately, a program was rapidly developed that reduced the likelihood of this virus and most of it was based on cultural practices. Over time, varieties that were less susceptible to the virus were developed and TSWV has been less of a problem the last ten years. However, it is still very much present in North Carolina and its suppression is dependent upon us following the cultural guidelines that the tomato spotted wilt virus risk index provides. Key factors include planting date, plant populations and row spacing, variety, insecticide use, and tillage. The value of utilizing the practices that reduce this virus is still very valuable.
There is preliminary evidence that indicates tomato spotted wilt virus risk will be higher in 2019. I repeat the word preliminary. In other words, based on what we now know, it appears that conditions are favorable for an increase. Not an epidemic, but an increase in its incidence. As a result, it is important to remind peanut growers that the cultural practices that reduce tomato spotted wilt virus are still very important even though we have not observed a high incidence of virus in recent year. Since these practices are primarily cultural in nature, they have to be implemented by planting time. For example, optimal planting dates to reduce virus are between May 6–15 and best plant densities are 5 or more plants per row foot. Once the crop is in the field, we really cannot impact the incidence of the disease. The virus management plan can be found on pages 93-96 in the 2019 Peanut Information publication.