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  • Author or Editor: David T. Handley x
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Corn earworm [CEW (Helicoverpa zea)] is one of the most important pests of sweet corn (Zea mays) in New England. Conventional management of this pest is achieved through repeated applications of chemical insecticides through the silking period. Organic growers, however, have few alternatives to prevent CEW infestation. Technology first developed in the 1930s and 1940s, using applications of mineral oil directly into the silk channel with an eyedropper, has been further researched in recent years using vegetable oils with and without pesticides, but pollination problems associated with these treatments have been observed. Several materials were evaluated for efficacy in controlling CEW populations and for phytotoxicity to the developing ear. Materials evaluated were corn oil, soy oil, carrageenan, corn oil mixed with Bacillus thuringiensis ssp. kurstaki (Bt), soy oil mixed with Bt, and carrageenan mixed with Bt. All treatments were compared with an untreated control. Treatments provided a range of 33% to 50% control of CEW infestation. The oil and Bt combinations provided some reduction in infestation compared with the untreated controls (33% vs. 100% infestation), but this level of control was inadequate for all wholesale markets and most direct markets. Additionally, oil-based treatments also caused significant injury to developing ears by reducing pollination quality, impacting the development of the kernels at the ear tip. This condition referred to as “cone-tip” is of concern since it may decrease marketability. The percent unmarketable ears due to cone-tips ranged from 0% to 13% for the untreated and carrageenan-based treatments. From 12% to 42% of ears were unmarketable due to the soy oil treatments. Corn oil treatments caused 10% to 50% cone-tips.

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Some Maine tomato growers use unheated greenhouses or high tunnels to extend the short growing season. But, what varieties should growers choose? The objective of this trial was to test varieties of greenhouse and open field tomatoes to identify the best performers in high tunnels in terms of yield, quality, disease, and taste. Results showed that both open field and greenhouse varieties produced similar and acceptable yields of high quality marketable fruit. Open field varieties showed more disease than greenhouse varieties. There were some significant differences between individual varieties. Betterboy scored highest in sensory analysis, but lowest in yield/quality. Brilliante scored poorly on marketable yields, but well in terms of premium yields, quality, disease and taste. It may be well suited for direct marketing to repeat customers (e.g., farmers' markets). For commercial production Jet Star, Brilliante, Cobra, and First Lady II appear to be good choices based on overall scores.

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Winter injury has limited the expansion of commercial blackberry (Genus Rubus, subgenus Rubus) production into more northern latitudes in central and eastern United States. Rowcover (RC) was applied over trailing ‘Boysenberry’ and ‘Siskiyou’ and erect, thornless ‘Triple Crown’ and ‘Apache’ blackberries at Kearneysville, WV (lat. 39.5°N, USDA Plant Hardiness Zone 6b) from 2004 to 2007. The daily minimum temperatures under RC were as much as 5 °F to 10 °F higher at nights after sunny days, but were similar during nights after overcast days. On sunny days, daily maximum temperatures under RC were as much as 28 °F higher than in the open. Under RC, humidity rose more quickly and remained higher during the day than in the open, but was slightly lower at night. Mean vapor pressure deficit in late December, January, February, and early March was 100 to 250 kPa higher under RC than in the open. RC treatment significantly reduced winter injury and increased yield in ‘Siskiyou’ blackberry plants. The winter protection techniques described here would provide substantial benefits for growing blackberries in more northern areas where winter injury frequently causes crop failure.

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