PPDL Picture of the Week
February 13, 2017
Wilt Virus and Impatiens Necrotic Spot Virus: Two Serious
Threats to Greenhouse Plantings
Ruhl, Sr. Plant Disease Diagnostician
closely related viruses, Tomato spotted wilt virus (TSWV) and
Impatiens necrotic spot virus (INSV), have an extremely wide host range and are
spread by thrips insects. Greenhouses
provide an excellent opportunity for thrips survival and population growth and
thus the presence of these viruses in greenhouse plantings pose
a serious threat to the greenhouse industry.
of TSWV/INSV vary depending on the host, the environmental conditions, and the
individual virus infecting the plant.
cause very heavy losses for growers producing greenhouse tomatoes.
Symptoms of TSWV on tomatoes include dark, brown necrotic spots on leaves, dark
streaks on stems, stunted growth and discolored fruit. Other vegetable
plants affected by TSWV include tomato, pepper, potato, eggplant, lettuce,
spinach and cucumber. Several ornamental plants are also affected by TSWV
and many weeds may serve as hosts. Thus,
greenhouse growers should avoid planting ornamentals in the same greenhouse as
vegetables since ornamentals can be provide a reservoir for TSWV and the areas
beneath the benches should be kept clear of weeds that may serve as virus
been confirmed on over 300 ornamental hosts and can produce a
wide variety of symptoms including etching, sunken spots, mosaic patterns or
ringspots on leaves; streaking and death of stems, wilting, stunting, and poor
often is difficult when it is based on symptoms alone since symptoms caused by
INSV and TSWV may resemble symptoms caused by fungal and bacterial diseases or
environmental stresses. Positive diagnosis using specialized serological testing
is necessary for confirmation of the presence of these viruses in plant tissue.
Plants with suspect virus symptoms may be submitted to the Purdue Plant and Pest Diagnostic Lab for serological testing to determine if a virus is present in the
of TSWV and INSV requires scouting for symptoms, accurate diagnosis,
destruction of infected plants and controlling the thrips vector using a
combination of insecticides and yellow sticky trap monitors.
Cornell e-Gro Alert: A Pictorial Guide to Common Symptoms of INSV in Greenhouse Crops
E - 110-W Western Flower Thrips