Tomato Spotted Wilt (TSW) Management in Peanuts
Tomato Spotted Wilt (TSW) is a topovirus that infects a wide range of plants in this area, including many native weed species. The virus is spread by a tiny, almost microscopic insect called a thrip. Damage to plants can be minor or result in death depending upon the strain of the virus, the growth stage of the plant and time of infection. Generally there are multiple species and high population of thrips with a huge range of weeds, field crops and ornamental plant hosts within Craven County. Thus, susceptible plants have a great risk of infection.
There are many factors that contribute to TSW incidence. First, and often overlooked, is the wide range of host weed plants found naturally within this area. If these weeds have low viral infection, then even when the thrip population is very high, TSW incidence may be very low. Secondly, the population of thrips is important since they are vector of the disease. Heavy rainfall events kill immature thrips thus decreasing the thrip population. Conversely, frequent but light rains result in lush, succulent plants that are attractive to thrips.
Control of thrips, and subsequently TSW, in peanuts is primarily accomplished through decisions made prior to or at planting. There is no pesticide treatment that will prevent or treat infections. Studies conducted throughout SE United States show that weed control in adjacent fields and repeated applications of insecticides to be highly ineffective and costly. All management of TSW for peanuts must be in preventative measures.
The major factors influencing TSW incidence are:
- Variety – Gregory, NC-V 11, Georgia Green and Bailey has shown to have less TSW while Perry has been shown to be very susceptible.
- Planting Date – Planting prior to May 5th has shown to place peanuts at high risk of TSW. Planting after May 10th decreases this risk. Late planted peanuts are often are very high risk of TSW.
- Tillage – Research shows that strip-tillage reduces TSW while conventional tillage may increase TSW.
- Higher Plant Population – Planting to obtain 5.0 plants per foot or in twin rows has shown to reduce TSW.
- In-furrow Insecticides – In furrow insecticides such as Thimet have shown to greatly reduce TSW.
- Early Season Thrip Control – Early season insecticide treatments have been shown to reduce TSW by keeping the thrip population low. Conversely, mid or late-season insecticides to control or reduce TSW has shown to be a waste of effort and money.
These cultural decisions should not be made based entirely on potential TSW alone. Simply put, many early season management decisions will effect late season insect and disease management as well as yield. To assist producers an Advisory Index has been created. Essentially, this system uses a scoring system based upon grower management decisions to provide a relative risk rating. Scores of 60 or less are low and a score of 90 or higher relates high risk. Download this tool below.
Download the publication, Managing Tomato Spotted Wilt Virus in Peanuts in North Carolina and Virginia
For more information regarding TSW management or peanut production, download the 2013 Peanut Information visit http://www.peanuts.ncsu.edu/
The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by the N.C. Cooperative Extension Service nor discrimination against similar products or services not mentioned. Individuals who use agricultural chemicals are responsible for ensuring that the intended use complies with current regulations and conform to the product label. Be sure to examine a current product label before applying any product.