Sweetpotato (Ipomea batatas L) was one crop chosen for development in Ontario in response to demand for alternative crops to tobacco and increasing demand for nontraditional vegetables. A wide range of vegetable crops can be grown in the sandy soils on the north shore of lake Erie. In 1999, there were ≈75 acres of sweetpotatoes grown in Ontario. Lack of an early cultivar to fit a short, warm season was a factor limiting production of sweetpotatoes in southern Ontario. Over an 11–growing season period, cultivars of sweetpotato from several breeding programs in the United States were evaluated for suitability to Ontario climatic conditions. Planting to harvest date season totals for heat units, precipitation, vapor pressure deficit (VPD), potential evapotranspiration, and solar radiation were calculated. Yield was regressed on these climatic variables using multiple linear regression. Of the cultivars evaluated, `Beauregard' replaced `Jewel' as the local industry standard after one season's evaluation. Of the numbered lines evaluated, NC9317 appears suitable for commercial trials. Yields varied greatly among years, and the seasonal VPD explained the largest amount of variation in year-to-year yield. Cultivars vary in their response to seasonal VPD. Yield of `Beauregard' increased with increasing seasonal VPD while NC9317 decreased. Cultivars require ability to yield in a short season and the ability to consistently produce under a range of atmospheric VPDs dictated by interannual climatic variation.
Strip tillage into killed rye (Secale cereale L.) and oats (Avena sativa L.) cover crops was evaluated as a production system for machine-harvested processing tomatoes (Lycopersicon esculentum Mill.). No effect of tillage on yield was found for 2 out of 3 years. Yield was reduced in the third year in strip-tilled rye plots due to low transplant vigor and possibly low-temperature injury. Populations of plant parasitic nematodes were stimulated by rye and strip tillage. Bacterial diseases were increased by strip tillage in one season. Long-term evaluation of conservation-oriented systems is required to determine effects on yield, nematodes, and diseases.
Because of the need to find plants that suppress root lesion nematodes for use in rotation or cover-crops, 16 native sand-prairie species were evaluated for host status for 6 years. Plants were grown on a Fox sand soil at a local prairie plant nursery. Soil cores were taken in the spring, summer, and fall and assayed for plant parasitic nematodes. Five species supported very low numbers (less than 100/kg soil) of root lesion nematodes. Brown-eyed Susan (Rudbeckia hirta) had no detectable nematodes for the duration. Switchgrass (Panicum virgatum L.) and Indiangrass (Sorghastrum nutans L., Nash) samples produced detectable nematodes on only two sampling dates over the 6 years and were statistically not different from brown-eyed Susan. Butterfly weed (Asclepias tuberosa L.) also had very low detectable nematodes as did sand dropseed [Sporobolus cryptandrus (Torr.) Gray.]. New Jersey tea (Ceanothus americanus L.), little bluestem [Schizachyrium scoparium (Michx.) Nash], and big bluestem (Andropogon gerardi Vitman) were poor hosts with <200 nematodes/kg soil. Mountain mint (Pycnanthemum virginianum L), wild bergamont (Monarda fistulosa L), horsemint (Monarda punctata L), and dwarf blazing star (Liatris cylindracea L) all had root lesion populations over 3000/kg soil. Horsemint and wild bergamont plants died out, possibly as a result of nematode infestation. Root lesion nematodes have an extremely wide host range in current agronomic and horticultural crops, and weeds and are difficult to manage using nonchemical means. Indiangrass, switchgrass, big bluestem, and little bluestem have all been used agriculturally for pastures and consequently have potential as beneficial long-term rotation crops for nematode management and soil building.
Cabbage (Brassica oleracea var. capitata, cv. Quick Green Storage) and carrots (Daucus carota L., Nantes type) were stored successfully in low pressure storage (LPS) at 50-60 Torr and 1° and 5°C with ‘Delicious’ apple fruit (Malus domestica Borkh.). LPS conditions minimized the effect of the ethylene produced by the apples on leaf senescence and abscission of cabbage, and formation of a bitter flavor in carrots.