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Title: INFECTION CUSHION FORMATION ON WEED SPECIES AND PEANUT FOLLOWING INOCULATION WITH SCLEROTINIA MINOR

Author
item MEADOR, C - OSU, DEPT. ENTOMOLOGY
item MELOUK, HASSAN

Submitted to: American Peanut Research and Education Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 5/15/2004
Publication Date: 12/1/2004
Citation: Meador, C.B., Melouk, H.A. 2004. Infection cushion formation on weed species and peanut following inoculation with Sclerotinia minor [abstract]. In: Proceedings of the American Peanut Research and Education Society, July 13-16, 2004, San Antonio, Texas. 36:21-22.

Interpretive Summary:

Technical Abstract: Formation of infection cushions as affected by five weed species and two peanut cultivars to Sclerotinia minor was evaluated by quantifying infection cushion formation on a cellophane membrane. Crownbeard, Eclipta, Jimsonweed, Pitted morningglory, Sicklepod, Okrun peanut (sclerotinia-susceptible), and Southwest runner (sclerotinia-resistant) were grown in the greenhouse for five or seven weeks. Plants were uprooted and root systems were rinsed with deionized water and placed in pouches made from dialysis tubing with a molecular weight cut-off of 12,000. Plants were then placed in Styrofoam cups (ca. 220 ml) containing 15 g perlite in which mycelial fragments of S. minor were mixed. Mycelial inoculum was prepared as follows: flasks containing 100 ml of potato dextrose broth were inoculated with three 0.6 cm mycelial plugs from a two-day-old culture of S. minor. Inoculated flasks were placed on a rotary shaker for five days. Mycelial mats were then collected by filtration, and 1 g of mycelia was fragmented in 100 ml of deionized water using a tissuemizer for 30 seconds at 20,000 rpm. Styrofoam cups were then placed in a humid chamber maintained at 24-29 C° and 100% relative humidity for five days. Plants were once again uprooted and the cellophane tubing was carefully removed and washed gently with cold tap water. A 5-cm long section was removed from the center of the cellophane tube and stained for 10 minutes with a 0.1% solution of Lactophenol Cotton Blue, then carefully rinsed with water and two sections were cut and placed on glass slides that each had four pre-marked 1 cm² areas. The infection cushions within the 1 cm² areas were counted under a compound light microscope. The untreated control consisted of a sleeve or dialysis tubing that contained no plant roots and was inoculated in the same manner as the plants. No infection cushions were found in the control. Okrun peanut, SW Runner peanut, and Pitted morningglory all stimulated production of significantly (p=0.05) higher numbers of infection cushions than any of the other weed species or control. Sicklepod, Crownbeard, Eclipta and Jimsonweed plants were not significantly different (p=0.05) from the control. Age was also significant with seven-week-old plants having significantly higher (p=0.05) numbers of infection cushions than five-week-old plants. These data suggest that at least some weed species are capable of stimulating the formation of infection cushions.