Plant cultivars of vegetables with resistance to Fusarium and Verticillium wilts. Cantaloupes, peas, and tomatoes have a wide selection of resistant varieties whereas other crops have limitations (Table 3).
Fusarium wilt affects tomato, eggplant and pepper. It can also survive on weeds such as pigweed, mallow and crabgrass. The fungus thrives in warmer weather (optimal soil temp 82°F) and is more severe in acidic soil. The pathogen most often enters through root wounds caused by cultivation or by nematode feeding.
Groups of plants resistant to verticillium wilt include gymnosperms, monocots, members of the rose family, oaks, dogwoods, willows, rhododendrons, azaleas, and others. Symptoms of verticillium wilt vary somewhat in different host species and also within species due to varying environmental conditions.
Tomatoes are usually the first choice for new gardeners. There are many disease resistant varieties including “Quick Pick”, “Champion”, “Better Boy” and “Supersteak”. These are all resistant to Fusarium wilt, Verticillium wilt and root knot nematodes.
Both fungi invade the plant through the fibrous root system and disrupt water and mineral uptake within the plant. Infection and disease development in Fusarium wilt are favored by warm soil temperatures (80° F) and low soil moisture, while Verticillium wilt develops best at relatively cool (55-75 F) soil temperatures.
The disease is favored by cool soil and air temperatures. Verticillium wilt is difficult to distinguish from Fusarium wilt and positive identification may require cultivating the fungus in a laboratory. Verticillium wilt seldom kills tomato plants but reduces their vigor and yield.
Plant cultivars of vegetables with resistance to Fusarium and Verticillium wilts. Cantaloupes, peas, and tomatoes have a wide selection of resistant varieties whereas other crops have limitations (Table 3).
Fusarium wilt affects the productivity of tomato plants and may lead to death, but the fruit is still edible.
There is no effective fungicide or other cure for Fusarium wilt. The pathogen nearly always kills infected hosts. Prevention and exclusion are the only effective management strategies. Avoid this problem by replanting at that site using species from different genera than plants previously infected there by Fusarium.
There are three strains of fusarium, the following are listed as having resistance to at least one. Resistant varieties for garden tomatoes: Sun Start, Sunny, Daybreak, Mt. Spring, Mt. Fresh, Celebrity, Floralina, Jet Star, Merced, Sunmaster, Sun Leaper, Carolina Gold.
Verticillium wilt can't be cured once it enters the plant. It's best to remove and destroy small, easily replaced plants. The disease remains in the soil after you remove the plant, so don't plant another susceptible species in the same area.
Avoid over-watering: Over-watering can increase the chances of Fusarium Wilt because the fungus thrives in moist soil.
Prothioconazole is the only commercially available fungicide with proven efficacy. Azoxystrobin, prothioconazole and thiophanate-methyl led to the highest values for reduction of Fusarium wilt and did not cause phytotoxicity in watermelons.
For Fusarium oxysporum f. sp. lactucae, the pathogen which causes Fusarium wilt of lettuce, the required temperature for control is generally taken to be > 140°F for 20 minutes.
How to Control Fusarium Wilt: Once fusarium wilt infects a plant, there is no effective treatment. Remove and dispose of affected plants immediately; don't compost this garden refuse. Whenever possible, remove and replace fusarium-infected garden soil.
Tomato is the solanaceous crop most frequently affected by a Fusarium wilt disease in Kentucky, but Fusarium wilts can also occur on eggplant and pepper. Affected cucurbit crops include cucumber, watermelon, and occasionally muskmelon.
Fusarium wilt disease is one of the most destructive diseases in cucumber. Fusarium solani and Fusarium oxysporum are the causative agents of the disease. Fusarium wilt disease of cucumber is highly prevalent in the field (10%–60% of disease incidence) with limited disease control.
There are now Fusarium resistant sweet basil cultivars available such as Aroma-2, Prospera and Obsession as well as others. If Fusarium wilt is introduced into the field growers should not grow any sweet basil or members of the mint family in that field for at least 2-3 years.
The beneficial soil-borne fungus Trichoderma harzianum strain T-22, which is sold as Trianum, can help keep Fusarium at bay. This fungus competes with Fusarium in the soil for nutrients and can even destroy this harmful fungus.
Symptoms and Signs
Initially, symptoms of Fusarium wilt of tomato appear as one-sided wilting of only half of the plant, branch, or leaflet. At first, the plant will appear to recover from the wilt, but as the disease progresses, it will become permanent regardless of temperature or water status.
The major differences in these wilts are: 1) The fungi proceed slowly in the host relative to bacteria and produce more uniform symptoms through the plant. 2) In bacterial wilt, symptoms appear from the top down, whereas in Fusarium and Verticillium wilt, symptoms begin at the bottom of the plant and progress upward.
Verticillium wilt can affect all cucurbits.