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Three taxa, Colletotrichum orbiculare, the unconfirmed teleomorph of C. orbiculare (Glomerella cingulata var. orbiculare), and C. magna, have been reported to cause anthracnose of cucurbits. In a previous study, virulence, vegetative compatibility, and mtDNA RFLPs have been used to examine these taxa. The three taxa can be distinguished based on mtDNA RFLPs. Under controlled greenhouse inoculation tests, only isolates of C. orbiculare (CO) from cucurbit hosts were highly virulent on cucurbit foliage; isolates of G. cingulata (GC) and C. magna (CM), and CO from cocklebur hosts were weakly virulent or avirulent. The majority of CM and GC isolates were recovered from fruit, whereas most CO isolates were recovered from foliage. A study was conducted to evaluate the pathogenicity and virulence of anthracnose isolates on cucurbit fruit. Twenty-seven isolates of the three taxa were selected based on the host and geographic origin, mtDNA RFLP haplotype, vegetative compatibility group, and race. Mature fruit from cucumber cultivars Marketer (susceptible) and H19 (resistant) and watermelon cultivars Black Diamond (susceptible) and Charleston Gray (resistant) were used. Fruit were inoculated by placing Torula yeast agar inoculum plugs (8mm in diameter) into wounds. Following inoculation, the wounds were covered with Parafilm and incubated for 8 days at 25C at 100% RH. On the third day the Parafilm was removed from the wound. Disease symptoms were evaluated by measuring lesion diameter and depth and evaluating the presence or absence of sporulation. All three anthracnose taxa are capable of infecting cucurbit fruit. CM and GC isolates were more virulent than CO isolates on cucumber. In contrast, on `Black Diamond', CO isolates were more virulent than CM and GC isolates. No significant differences in virulence were observed on `Charleston Gray'. There were no significant differences in virulence between the races of CO except on `Charleston Gray', where race 2 isolates were significantly more virulent than race 1. CO isolates from cocklebur were only weakly virulent on cucurbit fruit.

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Plastic mulch is commonly used by commercial producers of cucurbits because it increases soil temperature, reduces weed pressure, retains soil moisture, and increases earliness of harvest ( Lamont, 2005 ). Compared with bare ground systems, black

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Viruses are a serious threat to cucurbit production in southern Illinois. The most prevalent viruses infecting cucurbit crops in the region were determined during the 1998, 1999, and 2000 growing seasons to enable growers to make better decisions on viral disease management. Watermelon mosaic virus (WMV) was the most prevalent virus as it was found in ≈84% of samples over the three years. Cucumber mosaic virus (CMV), papaya ringspot virus (PRSV), squash mosaic virus (SqMV), and zucchini yellow mosaic virus (ZYMV) were detected in ≈8%, 6%, 9%, and 1% of samples, respectively, over the 3-year period. WMV was generally the only virus isolated from samples collected before mid-September. Other viruses, including CMV, PRSV, SqMV, and ZYMV, were generally first detected after mid-September and were usually found as mixed infections with WMV.

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Selecting production areas for low disease pressure, implementation of preventive spray programs, and continuous monitoring for disease symptoms are important steps to keep seed production fields free of potentially seedborne diseases, such as bacterial fruit blotch of cucurbits (Cucurbitaceae), caused by Acidovorax avenae ssp. citrulli. However, seeds of cucurbit crops and other fleshy vegetables typically remain remarkably free of pathogenic bacteria and fungi while in intact fruit. The most significant risk for seed contamination comes at harvest when the inoculum present in the field or in the seed harvesting area may contaminate the seeds. Properly executed fermentation and seed drying processes significantly reduce seed contamination. Application of a no-rinse disinfectant formulation to freshly harvested seed just before drying may be the single most efficacious procedure to reduce the seed contamination risk. However, the disinfection step should not be expected to be effective unless applied as part of a fully controlled seed harvest process.

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The cucurbits have several-fold size differences in their mitochondrial genomes. Watermelon possesses a relatively small mitochondrial genome of 330 kb. Squash has a larger mitochondrial genome of 840 kb. Cucumber and melon possess huge mitochondrial genomes of 1500 and 2400 kb, respectively. We demonstrated predominately paternal transmission of the mitochondrial genome in cucumber. Squash shows maternal transmission of the chloroplast genome. We generated reciprocal crosses and identified restriction fragment length polymorphisms in the chloroplast and mitochondrial genomes of melon, squash, and watermelon to establish their transmission. Our analyses also revealed that intergenomic transfers contributed to the evolution of extremely large mitochondrial genomes.

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Halosulfuron is a proposed alternative to methyl bromide for managing nutsedges (Cyperus spp.) in several vegetable crops, including cucurbits. Field studies were conducted to evaluate the crop sensitivity to halosulfuron in a spring squash (Cucurbita pepo L.)—fall cucumber (Cucumis sativus L.) rotation from 2000 to 2002. Treatments included application of halosulfuron to the soil surface after forming the bed, but before laying mulch (halosulfuron-PRE), halosulfuron applied through drip irrigation (halosulfuron-DRIP) after forming bed and laying mulch, metham applied through drip irrigation after forming bed and laying mulch, a nontreated control with mulch, and nontreated control without mulch. Each treatment was applied to both direct seeded and transplanted zucchini squash. Halosulfuron treatments reduced squash plant diameter relative to metham, however plant diameters in halosulfuron-PRE (transplant and direct seed) and halosulfuron-DRIP (transplant) treatments were not different from the nontreated control. Halosulfuron-PRE delayed squash fruit production relative to the mulched nontreated control. However, application of halosulfuron-PRE and halosulfuron-DRIP did not reduce squash yield at the conclusion of the season, relative to the nontreated control. Cucumbers were transplanted and direct seeded into previous squash plots and received either an application of halosulfuron-DRIP, or were not treated. Differences in cucumber yields were not detected with second crop treatments. Cucumbers appear to have adequate tolerance to halosulfuron, making it a potential replacement for methyl bromide for nutsedge control. Suppression of early season squash growth by halosulfuron may hinder the adoption of halosulfuron as a methyl bromide alternative for squash.

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Cucurbits comprise the highly diverse family known as Cucurbitaceae that includes cultivated, feral, and wild species ( Robinson and Decker-Walters, 1997 ). Many of the cultivated species such as squash ( Cucurbita ssp.), watermelon [ Citrullus

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Forty-four accessions of Cucumis melo L. and related wild species were tested for reaction to a yellowing disease, incited by the recently identified cucurbit yellowing stunting disorder virus (CYSDV), under natural and controlled-inoculation conditions. The C. melo TGR-1551 accession and one Cucumis metuliferus Naud. accession were asymptomatic. The segregation ratios obtained following controlled inoculations of the family produced by crossing TGR-1551 with the susceptible Spanish cv. Piel de Sapo revealed that the resistance to CYSDV in TGR-1551 is conditioned by a dominant allele at one locus. The name Cucurbit yellow stunting and symbol Cys is proposed for this locus.

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USVL531-MDR is a multiple disease-resistant (MDR) watermelon ( Citrullus mucosospermus ; Syn: Citrullus lanatus var. lanatus ) germplasm line that exhibits high levels of resistance to a broad range of isolates of cucurbit powdery mildew

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and flesh degradation are often evident when fruits are cut, affecting fruit marketability ( Adkins et al., 2007 ; Huber, 2006 ; Roberts et al., 2005 ). The known host range of SqVYV is limited to cucurbits, including several cucurbit weeds ( Adkins

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