Management strategies for Tomato spotted wilt virus and curtoviruses in Utah

Project Overview

Project Type: Professional + Producer
Funds awarded in 2019: $31,149.00
Projected End Date: 02/28/2022
Host Institution Award ID: G219-19-W7502
Grant Recipient: Utah State University
Region: Western
State: Utah
Principal Investigator:
Claudia Nischwitz
Utah State University
Dr. Diane Alston
Utah State University
Richard Heflebower
Utah State University Extension - Washington County


  • Vegetables: cucurbits, peppers, tomatoes


  • Education and Training: farmer to farmer, on-farm/ranch research
  • Pest Management: cultural control

    Proposal abstract:

    Vegetables are a $19 million industry in Utah and production acreage is expanding to accommodate grocery stores that want to offer more local produce. Tomato spotted wilt virus (TSWV), curtoviruses and their vectors are threatening the production of vegetables in Utah and neighboring states. Incidence of curtoviruses have always occurred in tomato and pepper production but has increased in recent years. In addition, the host range for curtoviruses has expanded to pumpkins and gourds with up to 25% losses in individual fields. TSWV incidence and yield losses quadrupled since 2012. Indications are the virus is established in the farmscape and transplant greenhouses and not introduced from out-of-state yearly. Annual losses for both viruses range from $1,300 to $6,600 per acre in fresh market production and $2,000-3,000 per 1,000 transplants for transplant producers. Management of these viruses is difficult. The objectives of this project are (1) to identify virus reservoirs near vegetable fields and in transplant greenhouses, (2) determine suitability of the identified virus reservoirs as reproductive hosts for the insect vectors and (3) evaluate floating row cover and reflective mulch as management options in on-farm trials, (4) develop outreach materials including field days with presentations by participating growers and Extension faculty and fact sheets. The expected outcome is that the control of identified virus reservoirs in the farmscape and in transplant greenhouses will reduce the incidence of TSWV and curtoviruses and minimize the distribution of virus infected transplants across the state. The use of floating row covers and reflective mulch will repel the insects and prevent them from feeding on vegetable crops and transmitting viruses especially early in the season when plants are most susceptible. These management strategies can be used by both organic and conventional producers.

    Project objectives from proposal:

    1. Identify TSWV and curtovirus reservoirs in the farmscape (ten fields) and greenhouse environment (five transplant operations) and determine their suitability as reproductive hosts for insect vectors (2019).

    Weeds have been identified as reservoirs for many viruses in many states but have not been evaluated in Utah. The survey will show which weeds are hosts to TSWV and curtoviruses. The insect vectors acquire the viruses as larvae. It is therefore necessary to determine the suitability of identified weeds as reproductive hosts for the insects. Good reproductive hosts are more likely a good source for virus dispersal and would be a priority for growers to remove from their fields and greenhouse operations. Controlled greenhouse studies will determine reproduction rates. Transplant producers will be less likely to sell infected plants and growers will see a reduction in TSWV and curly top in their fields.

    1. Evaluate the use of floating row covers as a tool to reduce curly top incidence. Participating growers will conduct field trials using floating row covers for tomatoes and peppers. Insect presence under row cover is monitored with sticky cards (2020).

    It is expected that floating row covers will reduce insect vector presence on covered plants and reduce curly top incidence.

    1. Evaluate the use of reflective plastic as a tool to reduce disease incidence. Growers will conduct field trials using reflective mulch for tomatoes, peppers and cucurbits. Insect presence in beds with reflective mulch vs black plastic mulch or no mulch is monitored with sticky cards (2020).

    It is expected that reflective mulch will reduce insect vector presence and reduce curly top and TSWV incidence.

    1. Deliver results of objectives 1-3 in on-farm field days (one each in Northern Utah and Southern Utah), fact sheets and presentations at other grower meetings (2020 and 2021).
    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.