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Identification of Fusarium solani f. sp. cucurbitae Race 1 and Race 2 with PCR and production of disease-free pumpkin seeds

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October 26, 2007

Source: Plant Disease magazine
October 2007, Volume 91, Number 10
Pages 1288-1292
DOI: 10.1094/PDIS-91-10-1288
Published by The American Phytopathological Society
http://apsjournals.apsnet.org/doi/interp/10.1094/PDIS-91-10-1288

Identification of Fusarium solani f. sp. cucurbitae Race 1 and Race 2 with PCR and Production of Disease-Free Pumpkin Seeds
H. L. Mehl and L. Epstein, Department of Plant Pathology, University of California, Davis 95616

ABSTRACT

Fusarium solani f. sp. cucurbitae causes a seedborne fruit rot of cucurbits and is classified into two races that are actually distinct species: F. solani f. sp. cucurbitae race 1 (Fsc1), which can infect the crown, roots, and fruit; and race 2 (Fsc2), which only infects fruit. Here, we report a polymerase chain reaction assay for rapid identification because cultures of Fsc1 and Fsc2 are not easily distinguished morphologically, and symptoms only on the fruit do not indicate that a F. solani f. sp. cucurbitae isolate is Fsc2; indeed, only Fsc1 was isolated from pumpkin fruit in California in fields in which growers observed symptoms only on the fruit. Planting of uninfected seed is critical for disease control. Because pumpkin seeds in the United States typically are purchased “as is,” without assurance that the seed is uninfected, recommendations that growers plant clean seed is scientifically sound but not helpful; contact fungicides such as thiram control the pathogen in F. solani f. sp. cucurbitae-infested seed, but do not control it in F. solani f. sp. cucurbitae-infected seed. In this article, we present evidence that cucurbit seed producers could restrict F. solani f. sp. cucurbitae-infected seed from their seed lots simply by visually examining fruit used for seed, and then excluding fruit with dry rot symptoms. In a 2-year study, no F. solani f. sp. cucurbitae-infected seed were recovered from fruit in which the surface was lesion-free or in which a lesion extended less than midway through the fruit flesh. Consequently, a rapid, visual inspection and exclusion of symptomatic fruit should be sufficient to obtain uninfected seed, even in infested fields.

Source: http://apsjournals.apsnet.org/doi/interp/10.1094/PDIS-91-10-1288

 

 

 

 

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