Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/10/1999
Publication Date: N/A
Interpretive Summary: Acremonium collapse is a newly described disease on muskmelon in Spain and is suspected of causing a similar disease in the upper San Joaquin and Sacramento Valleys of California. Intensive cultivation of cucurbit crops with inadequate rotation has resulted in an increase in both the number and severity of soilborne diseases involved in the vine decline complex and consequently has accounted for significant economic losses. Although Acremonium cucurbitacearum has been isolated from muskmelon and watermelon in the Rio Grande Valley of Texas, the disease is not considered to be a serious threat to Texas production at this time. Information was needed to determine if the fungus causing severe disease problems in Spain was different from the Texas isolates. Studies were also designed to determine the host range of a Texas and Spain isolate of Acremonium cucurbitacearum. Results demonstrated that the isolate from Spain was similar, if not identical, to the Texas isolate in virulence and host range. This strongl suggests that differences in disease severity between Spain and Texas is environmentally related. Watermelon and muskmelon were the most susceptible of the cucurbits tested. Some Cucurbita spp. demonstrated superior resistance to Acremonium cucurbitacearum. Consequently, these cucurbits should be evaluated as root stock for grafting muskmelon to control Acremonium collapse as well as other soilborne diseases.
Technical Abstract: Thirty nine species within the Cucurbitaceae Family, representing five genera, were evaluated for disease reaction to a Texas and Spain isolate of Acremonium cucurbitacearum. Disease reaction within the Cucurbitaceae ranged from highly resistant to highly susceptible. Leaf area may be a more sensitive index of plant damage to A. cucurbitacearum than root dry weight. Only two cucurbits were identified as highly resistant: Citrullus lanatus var. citroides and Cucurbita foetidissima. Luffa aegytiaca, Cucurbita maxima, Lagenaria siceraria, and Cucurbita. moschata were moderately resistant. The most striking result was that 15 of 19 cucurbits receiving the highest Disease Severity Ranking were in the genus Cucumis and Citrullus. These studies demonstrate that Cucurbita spp. have superior resistance to A. cucurbitacearum and perhaps should be evaluated as root stock for control of this and other vine declines. The Texas isolate appears to be similar in host range and virulence to a Spain isolate of A. cucurbitacearum.