HPIPM: Wilt, Near Wilt

Wilt, Near Wilt (Scientific name)

Author: Howard F. Schwartz, David H. Gent, Martha Mikkelson, and Jack Riesselman

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Cause

Wilt and near-wilt of pea is caused by the soiborne fungus Fusarium oxysporum f. sp. pisi. Certain races of the pathogen (races 1, 5, and 6) produce wilt symptoms; race 2 produces near-wilt symptoms. Races 5 and 6 are known to be economically important only in western Washington and southwest British Columbia. Races 1 and 2 occur throughout most pea growing regions of the US.

Symptoms

Wilt symptoms appear as yellow and stunted plants. Leaves tend to curl and wilt, usually in definite areas within the planting. Often, the vascular system is reddish to yellow-brown, especially at the nodal area of the stem.

Impact of Disease

Near-wilt caused by race 2 usually occurs in scattered plants in the field (1 to 3% incidence) and is evident when the plant approaches green or canning maturity. Near-wilt can be severe when susceptible cultivars are grown in short rotations.

Life Cycle of the Pathogen

The pathogen is an efficient soil saprophyte, and can colonize the roots of many plants, including nonhosts and resistant pea varieties. Disease is initiated when soilborne resting structures (chlamydospores) germinate and infect fibrous roots, growing into the water-conducting tissues of the plant. The pathogen reproduces in and on roots of susceptible and resistant pea. Wilt and near-wilt are most severe when soil temperature are near 68ºF. The pathogen can be disseminated among fields by the movement of contaminated soil and plant parts by equipment, wind, water, and infested seed. F. oxysporum survives between pea crops in the soil as chlamydospores, on the roots of weeds and alternate hosts, and as a saprophyte on decaying organic matter.

Management Approaches

Biological Control

No biological control strategies have been developed for wilt and near-wilt of pea.

Cultural Management Practices

Resistant varieties are available and effectively control wilt and near-wilt, but must be used along with a five-year or longer crop rotation to be most effective. Race-specific and race-nonspecific resistance is available, but race-nonspecific resistance often breaks down when disease pressure is high. If susceptible varieties are grown, they should be planted early to avoid soil temperatures favorable for the pathogen.

Chemical Management Program

No chemical controls are necessary for wilt and near-wilt management.

Consult pesticide labels for additional rate, application, and safety information. Additional information and current labels can be found at http://www.greenbook.net or http://www.cdms.net.

References

The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality.