Cucumber mosaic virus (CMV) is a major component of the virus complex that has become more pronounced in snap bean in the midwestern and northeastern United States since 2001. Multiple-vector-transfer tests were done to estimate the CMV transmission efficiencies (p) of the main aphid species identified in commercial snap bean fields in New York and Pennsylvania. The four most efficient vectors (p > 0.05) were Aphis gossypii, A. glycines, Acyrthosiphon pisum, and Therioaphis trifolii, which were all significant species in the migratory aphid populations in snap bean. Moderately efficient vectors (0.01 < p < 0.04) were A. spiraecola, A. craccivora, Macrosiphum euphorbiae, and Rhopalosiphum maidis. Poor vectors (p < 0.01) included A. fabae, Nearctaphis bakeri, and Myzus persicae. Only one species, Sitobion avenae, failed to transmit CMV in replicated tests. Estimates of p were consistent between different clones of the same aphid species and among three different field isolates of CMV tested. Single-vector-transfer test results for a subset of the species supported those obtained via the multiple-vector-transfer approach. Our results are consistent with the notion that A. glycines is a major vector of recent CMV epidemics in snap bean, but that species is only one of several that are involved.
Sclerotinia blight of peanut, caused by Sclerotinia minor, generally becomes severe only after vines meet in the row middles and a dense canopy develops. Dense foliage appears to support a microclimate conducive to the colonization of peanut limbs by S. minor. Removal of excess foliage before and during a Sclerotinia blight epidemic on the susceptible genotype NC 7 has been shown to reduce the rate of disease progress. Field tests in 1993 and 1994 examined control of Sclerotinia blight among four peanut genotypes (NC 7, VA 93B, NC Ac 18016, and Tam-span 90) with diverse canopy morphologies. Each cultivar had foliage pruned with a rotary mower once (1993 and 1994) or twice (1994) during the season. Applications of fluazinam (9.2 kg a.i./ha) were imposed on the genotype × pruning treatments. Soil temperatures under the canopy of each genotype and pruning treatment were measured and compared. Disease data were collected weekly by counting the number of feet of plants exhibiting lesions with visible fungus growth. Tamspan 90, a resistant Spanish peanut, had the least Sclerotinia blight incidence. Pruning measurably affected soil temperature for approximately 2 weeks following pruning. Removal of foliage reduced disease and increased disease control affected by fluazi-nam in fields with high disease pressure. In some tests, yields were increased by pruning through a reduction in disease pressure. Yields were lower when peanuts were pruned excessively, especially late in the season. Pruning of excessive vine growth can be an alternative, or complement, to fungicide treatments when done in midseason during favorable weather when moderate to high disease pressure occurs.
Selecting vegetable cultivars suitable to local environmental conditions and with quality traits desired by the evolving market and consumer needs is an important production decision farmers face annually. As seed companies continue to expand their offerings of new cultivars and rootstocks, selecting the best cultivar and/or scion/rootstock combination can be challenging for farmers. Land-grant universities, through their integrated research and extension programs, can provide an unbiased, science-based evaluation of the available cultivar and rootstock options to assist farmers in making this important selection. A two-year study was conducted to evaluate 20 hybrid cultivars and two grafted entries of muskmelons at three locations in Pennsylvania in 2018 and 2019 to provide farmers with science-based recommendations focused on fruit yield and physicochemical quality characteristics. Most cultivars did not differ in fruit yields from the standard “Aphrodite”. “Sugar Cube” produced more, smaller sized melons than “Aphrodite”. However, the combination of the soluble solids concentration, flesh pH, and titratable acidity values was not as favorable, indicating that consumer preference may be lower for “Sugar Cube” than for other cultivars. Yield from grafted entries was not different from the non-grafted “Aphrodite”; although, biotic and abiotic stressors favoring the use of grafting were not present throughout the study. Physicochemical evaluation of the combination of “Aphrodite” scion and “Flexifort” rootstock was more favorable than “Aphrodite/RS841” and non-grafted “Aphrodite”. This combination may be desirable even in the absence of yield stressors.
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