Andy Wyenandt

This is an archive of Dr. Wyenandt's posts on the Plant and Pest Advisory.

January 7, 2020

Understanding and Controlling Tomato Brown Rugose Fruit Virus

Tomato Brown Rugose Fruit Virus (ToBRFV) is an emerging virus in greenhouse tomato production worldwide. The virus was first identified in Israel a few years ago and has since been found in Europe, Asia, Mexico, and the US.  The pathogen is known to be present in greenhouse tomatoes in Mexico, and has occasionally been found in field tomatoes grown there (UMASS); it has also been found on imported fruit in FL (Also see VGN story below). An outbreak was reported (and contained) in CA in early 2019 but, unfortunately, the virus was found in greenhouse tomato production in New Jersey this past fall.

ToBRFV is more severe on young tomato plants and can result in 30-70% yield loss (UFL). Foliar symptoms of ToBRFV on tomato and pepper include deformed, crinkled leaves, mosaic, mottling, flecking, chlorosis, and/or necrosis (see images). Fruit symptoms include discoloration and rough brown patches or ringspots. Irregular fruit shape and maturation patterns may also occur. Browning of the veins in the fruit calyx in the early stages of fruit ripening may also be observed. Symptom expression can vary widely among tomato cultivars (UMASS); while some green fruit may be infected but remain asymptomatic until the fruit starts to ripen.

ToBRFV is a member of the tobamovirus family along with tobacco mosaic (TMV), tomato mosaic (ToMV), and tomato mottle mosaic (ToMMV). ToBRFV is especially worrisome for tomato growers because it has overcome the Tm-22 gene that confers resistance to tobamoviruses in many tomato cultivars. Like TMV, ToBRFV is very stable and easily transmitted by mechanical means; in a highly managed crop such as greenhouse tomatoes, this means that human activity is the primary vector. The virus may also be transmitted mechanically by bumble bees employed to pollinate greenhouse crops. The virus can be seedborne and research indicates that it is associated with the seed coat, not the embryo. This means that treatments such as hot water or steam should be effective in removing the virus from seed (UMASS).

Management practices for ToBRFV include planting of disease free seed and seedlings, scouting plants regularly for symptoms, and isolating symptomatic plants. Disinfect tools and workers’ hands frequently. Recent research has demonstrated that the most effective disinfectants include 10% bleach, 50% Lysol, and 20% nonfat dry milk (UMASS). Currently, no commercial tomato varieties are tolerant to ToBRFV. Peppers with tolerance to TMV and pepper mild mottle virus (PMMoV) have shown some tolerance (MSU). ToBRFV’s high stability allows it to stay infectious in the soil, in plant debris and on stakes for long periods—up to 20 years. There are reports of spread by bumble bee pollinators in greenhouse situations. However, there are no reports of plant-to-plant transmission by aphids, leafhoppers or white flies (MSU).

There are no sprays that can be applied that are effective in helping to reduce the virus’s spread. Seed and transplant production are the most critical steps since contamination at these steps may create a risk of further contamination (MSU). A number of County Offices have the equipment for doing the hot water seed treatment method. Please contact your county agent for more information. Importantly, as a note, there is very limited to no information on infested seed sources, with only a few greenhouse tomato cultivars with known problems.

Recommended actions include (from MSU):

  • Start with certified clean or treated seed from a reputable dealer. Do not purchase seed from unverified sources, especially if they come from known restricted areas.
  • Have greenhouse workers wash and sterilize hands and tools often.
  • Supply single-use gloves that are discarded between greenhouse ranges.
  • Provide protective clothing that stays in that greenhouse range or that is well washed before going to another range.
  • Dispose of symptomatic plants and plants within 5 feet of infected plants. Also, dispose of plants, strings, trays and media through incineration—DO NOT spread it out on your fields (or reuse it for other crops in the greenhouse)!
  • Monitor movement of equipment and workers between fields. Thoroughly wash equipment and possibly have workers bring a change of clothes.
  • Rogue and incinerate symptomatic plants and conduct any daily activity last in that greenhouse followed by good sanitation.

On November 15, 2019, USDA/APHIS issued an emergency federal order that calls for pre-export testing of tomato and pepper propagative material (plants, seeds, grafts, and cuttings) and fruit produced in any country where ToBRFV has been detected; to date, this list includes Israel, Jordan, Turkey, Greece, Italy, the United Kingdom, the Netherlands, China, and Mexico. Countries where ToBRFV has not been reported may state this fact by providing a letter from the nation’s plant protection organization: propagative material and fruit exported to the USA will then be exempt from the testing requirement. Tomato and pepper fruit from Canada will also be subject to inspection prior to export, because Canada imports these crops from Mexico and re-exports them to the US. US Customs and Border Protection will also increase inspections at U.S. ports of entry to ensure imported tomato and pepper fruit from Mexico, Israel, the Netherlands, and Canada are free from symptoms of ToBRFV. (UMASS, USDA)

The NJDA, in cooperation with USDA APHIS PPQ, has been assisting affected NJ tomato producers in identifying critical control points and implementing the best management practices necessary to reduce the threat of introducing Tomato Brown Rugose Fruit Virus (ToBRFV) into future production. Tomato growers in New Jersey who suspect ToBRFV are encouraged to contact their county agent and the NJDA Division of Plant Industry. The NJDA is working with USDA APHIS PPQ to establishing testing protocols and will facilitate the screening of suspect plants.

References:

Dr. Anglela Madeiras (UMass)

http://ag.umass.edu/greenhouse-floriculture/fact-sheets/tomato-brown-rugose-fruit-virus-tobrfv

Dr. Ron Goldy (Michigan State University)

https://www.canr.msu.edu/news/tobrfv-a-new-concern-for-tomato-and-pepper-producers

Kendall Stacy (University of Florida)

http://blogs.ifas.ufl.edu/pestalert/2019/07/23/tomato-brown-rugose-fruit-virus/

American Seed Trade Association

https://www.betterseed.org/wp-content/uploads/ToBRFV-QA.pdf

USDA/APHIS

https://www.aphis.usda.gov/aphis/newsroom/stakeholder-info/sa_by_date/2019/sa-11/tomato-brown-rugose-fruit-virus

Vegetable Grower News – Tomato Brown Rugose Virus Concerns Growers

Filed Under: Commercial Ag Updates, Vegetable Crops
September 18, 2019

Vegetable Disease Update – 9/17/19

  • All cucurbit growers are encouraged to scout their fields on a regular basis and continue to use a downy mildew specific fungicide program. Fungicides that are specific to CDM should be included in weekly fungicide maintenance programs for cucurbit powdery mildew control. To track the progress of CDM in the US please visit the CDMpipe forecasting website here.
  • Basil downy mildew has been reported in New Jersey on BDM susceptible and resistant sweet basil lines. All basil growers should continue to scout and follow a BDM specific fungicide program even when using DMR varieties. To track the progress of BDM in the US please visit here.
  • Downy mildew has been reported in turnip greens. Growers who have fall leafy greens and cole crops should scout daily and be proactive and initiate a regular downy mildew specific fungicide program. Although its been relatively dry, spotty showers, cooler nights, and longer periods of dew (leaf wetness) have made conditions ideal for downy mildew development across a number of susceptible crops.
  • Pepper anthracnose continues to be reported.
  • The 2019 Fungicide Resistance Management Guide for Vegetable Crops in the mid-Atlantic Region is now available for FREE online.
  • For more information on controlling these and other important diseases please see the 2019 Mid-Atlantic Commercial Vegetable Production Guide. The guide is available for FREE online by following the links on the Plant and Pest Advisory website. Hardcopies of the 2019 guide can be purchased through your local county Extension office.
Filed Under: Vegetable Crops
August 2, 2019

Vegetable Disease Update – 8/2/19

  • Cucurbit downy mildew was been reported on pumpkin in Warren County this week. All cucurbit growers are encouraged to scout their fields on a regular basis and to initiate a downy mildew specific fungicide program. This is the first report of CDM on pumpkin in New Jersey this growing season. Fungicides that are specific to CDM should be included in weekly fungicide maintenance programs for cucurbit powdery mildew control. To track the progress of CDM in the US please visit the CDMpipe forecasting website here.
  • There have been a few reports of Southern blight (Sclerotinia rolfsii) on tomato and pepper. Southern blight is much more common in vegetable areas south of the state where summer temperatures remain hotter (above 90°F) for longer periods of time. Like white mold, caused by Sclerotinia sclerotiorum, it can survive in the soil for many years. Symptoms of Southern blight include infection at the base of the stem at the soil-line. The resulting infection will girdle the plant causing wilt and death. The fungus will produce white, cottony mycelium and very small, spherical sclerotia which are often have a tannish, brown color.
  • Cercospora leaf blight has been reported in a newly planted asparagus field.
  • Corn leaf rust has been reported in northern New Jersey.
  • Basil downy mildew has been reported in New Jersey on BDM susceptible sweet basil lines. All basil growers are encouraged to initiate a BDM specific fungicide program even when using DMR varieties. To track the progress of BDM in the US please visit here.
  • Phytophthora blight has been reported in pepper and other crops.
  • Bacterial leaf spot has been widely reported in pepper plantings.
  • The 2019 Fungicide Resistance Management Guide for Vegetable Crops in the mid-Atlantic Region is now available for FREE online.
  • For more information on controlling these and other important diseases please see the 2019 Mid-Atlantic Commercial Vegetable Production Guide. The guide is available for FREE online by following the links on the Plant and Pest Advisory website. Hardcopies of the 2019 guide can be purchased through your local county Extension office.
Filed Under: Vegetable Crops
August 2, 2019

Controlling important fungal diseases in Asparagus during the summer.

Asparagus growers should consider scouting their fields during the summer months for  foliar disease development. Important pathogens that growers need to scout for on a regular basis include Purple spot, Cercospora, and Rust. [Read more…]

Filed Under: Vegetable Crops Tagged With: ,
July 19, 2019

Cucurbit Downy Mildew Alert – 7/19/19

Cucurbit downy mildew has been reported on winter squash near Glassboro in southern New Jersey (Gloucester County). This is the third report of CDM this growing season in the state. All cucurbit growers are encouraged to scout fields on a daily basis and begin preventative fungicide programs if already not initiated.

Filed Under: Vegetable Crops
July 17, 2019

Vegetable Disease Update – 7/17/19

  • Cucurbit downy mildew has been reported on butternut squash in Gloucester County this week. All cucurbit growers are encouraged to scout their fields on a regular basis and to initiate a downy mildew specific fungicide program. This is the first report of CDM in butternut squash in New Jersey this growing season. To track the progress of CDM in the US please visit the CDMpipe forecasting website here.
  • There have been no reports of late blight in the region to date. Phytophthora nicotianae has been reported in the region in recent weeks. Symptoms caused by P. nicotianae look similar to late blight. If you suspect late blight on potato or tomato please contact your county Extension office.
  • Basil downy mildew has been reported in southern New Jersey on BDM susceptible sweet basil lines. All basil growers are encouraged to initiate a BDM specific fungicide program. To track the progress of BDM in the US please visit here.
  • Black leg symptoms have been reported on potato vines. Growers should dig up a few hills with aerial black leg symptoms to see if bacteria has worked its way into developing tubers. If tubers “stink” then traditional black leg is present. If rotten tubers are present and have no smell, please contact your County agent so samples can be collected and tested.
  • Bacterial leaf spot has been reported in tomato and pepper.
  • Phytophthora blight has been reported in pepper and other crops.
  • Angular leaf spot has been reported on cucurbit crops. Click here for a nice review of diagnosing angular leaf spot, bacterial leaf blight, downy mildew, and anthracnose in cucurbit crops from Dr. Beth Gugino, vegetable pathologist, at Penn State.
  • Cucurbit powdery mildew has been reported. Apply and rotate fungicides that are specific for CPM control.
  • The 2019 Fungicide Resistance Management Guide for Vegetable Crops in the mid-Atlantic Region is now available for FREE online.
  • For more information on controlling these and other important diseases please see the 2019 Mid-Atlantic Commercial Vegetable Production Guide. The guide is available for FREE online by following the links on the Plant and Pest Advisory website. Hardcopies of the 2019 guide can be purchased through your local county Extension office.
Filed Under: Vegetable Crops