Chickpea (Garbanzo Bean) (Cicer arietinum)-Sclerotinia Stem Rot (White Mold)


Cause The fungi, Sclerotinia sclerotiorum and S. trifoliorum, can cause stem rot of chickpea. Both fungi overwinter as small black structures (sclerotia) in soil. Sclerotia may survive 5 to 8 years in the soil. After a conditioning period of several weeks at 40°F in moist soil, sclerotia can germinate in moist soil when temperatures are 59°F to 65°F and produce a small, stalked, cup-shaped fruiting structure (apothecium; plural: apothecia), which releases millions of spores into the air. Sporulating apothecia can persist 5 to 10 days. Spores are forcibly ejected and a few may be blown up to a mile but most land nearby. Spores can survive 2 weeks. Under moist conditions, spores may infect senescent tissue such as blossoms and leaves or may germinate and colonize plant debris. After colonizing blossoms or senescing leaves, the fungus can invade any healthy part of the plant it contacts. Moist conditions within the plant canopy favor infection. Rain, dew, and/or irrigation practices that keep foliage wet for long periods favor white mold development.

Other host plants of S. sclerotiorum number around 400 plant species, including dry and snap bean, pea, lettuce, carrot, cabbage and other crucifers, parsnip, potato, sunflower, radish, and cucurbits while dandelion (Taraxacum officinale) is a very susceptible weed host. The major host plants for S. trifoliorum include alfalfa and clover.

Symptoms The first symptom is usually discoloration of the stem. Either fungus may invade the stem near the soil line or approximately 6 inches above the ground, girdling of the stem aboveground, followed by wilt symptoms and death of the entire plant. A fluffy, white mold may be found on the surrounding soil surface or lower stem when plants are infected at the soil line and such plants frequently have black sclerotia associated with external tissues or surrounding soil. When stems are affected higher up, rarely are sclerotia or the white, moldy growth visible.

Cultural control

  • Plant on spacing that allows better air circulation between plants, thus permitting better drying of the soil surface and plant canopy and providing unfavorable environmental conditions for Sclerotinia. Space plants for good aeration between and within rows and orient to the prevailing wind if the placement of irrigation equipment allows.
  • Do not over-irrigate. After seeds start to form, allow soil surface to dry out before irrigating again or cease irrigation altogether.
  • Apply adequate nitrogen for crop needs, but not apply excessive fertilizer that leads to dense, lush plant growth that is favorable for Sclerotinia.
  • Plowing deeply to bury sclerotia may be beneficial once the pathogen is in a field, but plowing the field in later years may return viable sclerotia to the surface where they can produce apothecia.
  • Practice crop rotation by growing nonsusceptible crops (grasses and cereals) for 8 to 9 years, before planting susceptible crops (alfalfa, clover, bean, lettuce, potato, crucifers, celery, etc.).

Chemical control Applications after the disease is widespread in the field will not satisfactorily control the disease.

  • Cannonball WP (Group 12) at 7 oz/A when 10% to 20% of the plants have at least one (1) open blossom. Preharvest interval is 7 days. 12-hr reentry.
  • Carboxamide (Group 7) formulations are registered for use. Do not make more than two (2) sequential applications before alternating to a labeled fungicide with a different mode of action.
    • Endura at 8 to 11 oz/A. Preharvest interval is 21 days. 12-hr reentry.
    • Vertisan at 16 to 20 fl oz/A. Preharvest interval is 21 days for seeds; 0 days for hay. 12-hr reentry.
  • LifeGard WG (Group P6) at 1 to 4.5 oz/A on 7- to 14-day intervals for activating plant resistance. Refer to label for appropriate rate per application volume. Preharvest interval is 0 days. 4-hr reentry. O
  • Switch 62.5WG (Group 12 + 9) at 11 to 14 oz/A. Apply when 10% to 20% of plants have at least one open bloom and again 7 days later. No more than two (2) sequential applications. Do not apply within 7 days of harvest. 12-hr reentry.
  • Thiophanate-methyl formulations (Group 1) are very effective on Sclerotinia, and several are labeled for chickpea.
    • T-Methyl 4.5F AG at 30 to 40 fl oz/A. Make first application when 10% to 30% of plants have at least one open bloom and again no earlier than 7 days later. May be applied by ground or air. Preharvest interval is 28 days. 12-hr reentry.

Biological control

  • Amplitude at 2 to 4 quarts/A on 7- to 10-day intervals. Preharvest interval is 0 days. 4-hr reentry. O
  • Contans WG at 1 to 4 lb/A, depending on depth of incorporation, as a preplant or postharvest treatment. Incorporate thoroughly in the top 2 inches of soil. 4-hr reentry. Studies in snap bean show that protective fungicides are still required as only a few sclerotia are needed to cause an epidemic in a field. O
  • Double Nickel LC at 0.5 to 4.5 pints/A at planting and again at cultivation, can repeat on 10- to 14-day intervals. Can be applied the day of harvest. 4-hr reentry. O
  • Serenade Opti at 14 to 20 oz/A on 7- to 10-day intervals. Applications can be made up to and the day of harvest. 4-hr reentry. O
  • Stargus at 2 to 4 quarts/A plus a nonionic surfactant on 7- to 10-day intervals. Preharvest interval is 0 days. 4-hr reentry. O

Reference Njambere, E.N., Chen, W., Frate, C., Wu, B.M., Temple, S.R., and Muehlbauer, F.J. 2008. Stem and crown rot of chickpea in California caused by Sclerotinia trifoliorum. Plant Disease 92:917-922.