Open AccessEffect of Soil Inoculum Density of Fusarium oxysporum f. sp. vasinfectum Race 4 on Disease Development in Cotton
Author(s) -
Jianjun Hao,
Mary E. Yang,
R. M. Davis
Publication year - 2009
Publication title -
plant disease
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.663
H-Index - 108
eISSN - 1943-7692
pISSN - 0191-2917
DOI - 10.1094/pdis-93-12-1324
Subject(s) - biology , fusarium oxysporum , potting soil , potting , conidium , fusarium wilt , horticulture , cultivar , inoculation , shoot , fusarium , botany , computer science , embedded system
The effect of soil inoculum density (0 to 10 6 conidia/g of potting mix) of Fusarium oxysporum f. sp. vasinfectum race 4 on plant growth (weight, height, and number of nodes), Fusarium wilt symptoms, vascular discoloration, and number of CFU per gram of stem tissue was determined on five cotton cultivars grown in a greenhouse. In the susceptible cv. DP744, symptoms of wilt and reductions in plant growth occurred at inoculum levels of 10 3 conidia/g of potting mix and higher, whereas plant growth of the resistant Pima cv. Ph800 was not affected by any soil inoculum densities. Cvs. DP340, Ph72, and UltEF all responded similarly, with a relatively moderate negative growth response to soil inoculum densities generally beginning at 10 4 conidia/g of potting mix. F. oxysporum f. sp. vasinfectum race 4 was recovered from the stems of all cultivars by plating macerated stem tissue on a semiselective medium. There was a significant positive correlation between CFU and inoculum density above 10 4 conidia/g of potting mix for DP744 and UltEF. The fungus was recovered relatively infrequently from stems of Ph 800 plants inoculated with any inoculum density of F. oxysporum f. sp. vasinfectum. Fusarium wilt caused by F. oxysporum f. sp. vasinfectum race 4 is an inoculum density- dependent disease; the disease was generally mild and the fungus was rarely recovered from stems at inoculum levels less than 10 4 conidia/g of potting mix.