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- Author or Editor: Bernard H. Zandstra x
One of the most important decisions a grower makes when formulating plans for planting is what cultivar to select. The experienced grower has observed the evolution of cultivars and is intensely aware of the vast improvements that have been made through plant breeding. Much of the increase in crop productivity can be attributed to the disease resistance, environmental adaptability, and increased yield potential incorporated into cultivars by public and private plant breeders.
Small grains are interseeded with several vegetable crops in Michigan to protect them from wind and water erosion. When the vegetable crop is well-established, the small grain is killed with a graminicide. Research was conducted to determine the optimum combination of small grain species, age of kill, and nitrogen application rate for acceptable pickling cucumber yield in a single harvest. In several experiments, barley, oats, rye, and wheat were seeded at 130 seeds/m2 in the field. Cucumbers were seeded 1 week later. The cover crops were treated with sethoxydim at 0.21 or 0.31 kg·ha–1 plus 1.25% COC when they were 7 to 10 or 13 to 16 cm tall. Small grain size at application had no effect on their kill with sethoxydim or on cucumber yields. Barley and rye were the most vigorous small grains up to 3 weeks after seeding, but oats were similar in size by 4 weeks. Wheat was slower to develop, and more difficult to kill with sethoxydim. The optimum nitrogen treatment was 34 kg·ha–1 before planting the cover crop, followed by 45 kg·ha–1 at the two- to three-leaf stage of cucumber.
‘Pik-Red’ tomato (Lycopersicon esculentum Mill.) transplants produced in 2 locations (Florida and Michigan), in 6 root cell sizes were compared for fruit productivity in Michigan. Transplants grown in large cells produced more early yields than those from small cells, but generally did not produce more total yields. Large root cell size had a greater effect on transplant size than did wide spacing in the flat. Speedling root cell size 175 (39.5 cm3) produced the largest transplants, the largest early fruit yields, and the greatest weight of marketable fruit. Transplants grown in Speedling trays in Michigan produced larger early yields than Speedling transplants grown in Florida.
Four studies were conducted from 2001 to 2004 in Michigan to determine Christmas tree tolerance and weed control with flumioxazin and other herbicide treatments. In Study 1, fraser fir (Abies fraseri) leader length was greater with fall-applied flumioxazin (0.38 lb/acre) than with halosulfuron (0.21 lb/acre), isoxaben (1 lb/acre), oxyfluorfen (1 lb/acre), simazine (2 lb/acre), or sulfentrazone (0.5 lb/acre). Flumioxazin applied in the fall provided preemergent control of common ragweed (Ambrosia artemisiifolia), field violet (Viola arvensis), and hoary alyssum (Berteroa incana) 79% to 98% the following summer. Preemergence weed control with the other herbicides was more variable. In Study 2, fraser fir treated in the spring with oxyfluorfen had the shortest leader length (terminal stem growth of the current growing season) at 4.3 inches. Trees treated in the spring with flumioxazin, isoxaben, simazine, and sulfentrazone had leader lengths of 6.7 to 8.7 inches. Flumioxazin applied preemergence in the spring controlled common ragweed 80%, but controlled field violet, hoary alyssum, and white campion (Silene alba) only 43% to 64%. In Study 3, fall-applied flumioxazin alone did not injure colorado blue spruce (Picea pungens). However, mixtures of flumioxazin plus pendimethalin (3 lb/acre) caused 5% and 6% tree injury at 6 months after treatment (MAT) and sulfentrazone plus pendimethalin caused 9% and 23% injury at 6 MAT in 2003 and 2004, and 52% injury at 9 MAT in 2004. There was no significant injury to the trees treated with isoxaben plus pendimethalin, oxyfluorfen plus pendimethalin, or simazine plus pendimethalin in 2003 and 2004. Leader length was reduced by sulfentrazone plus pendimethalin compared with flumioxazin plus pendimethalin and oxyfluorfen plus pendimethalin. Flumioxazin plus pendimethalin provided 84% to 88% preemergence control of annual grasses, common catsear (Hypochoeris radicata), horseweed (Conyza canadensis), and virginia pepperweed (Lepidium virginicum). In Study 4, spring-applied mixtures of flumioxazin plus pendimethalin resulted in minor (2%–10%) visual injury to colorado blue spruce, although leader length at the end of the season did not differ significantly from the control. In summary, flumioxazin controlled several weed species with acceptable selectivity in colorado blue spruce and fraser fir Christmas trees.
Carrots (Daucus carota L.) or onions (Allium cepa L.) were interplanted with barley (Hordeum vulgare L.) or rye (Secale cereale L.) seeded at 0, 0.5, 1.0, or 2.0 bushels/acre (0, 43.5, 87, and 174 liters-ha-i). Barley was killed at heights of 4, 8, 12, or 16 inches (10, 20, 30, or 40 cm), and rye was killed at 4, 6, 7, or 8 inches with a postemergence graminicide. Barley and rye killed at 4 inches did not reduce onion yield. If barley exceeded 8 inches and rye exceeded 7 inches when killed, onion yields were reduced. Carrot yield was reduced only by 2 bushels of barley killed at 16 inches. One bushel of barley per acre killed at 4 inches appeared to be optimal in giving good soil protection and minimal crop competition.
‘Pik-Red’ tomato (Lycopersicon esculentum Mill.) transplants grown in the greenhouse were fertilized with three levels of N and P. Nitrogen at 400 mg·liter-1 and P at 30 mg·liter-1 had produced the largest transplants at 5 weeks after sowing. Nitrogen at 100 mg·liter-1 produced the largest root : shoot ratio. Phosphorus had no effect on root : shoot ratios. Plants fertilized with moderate and high N levels in the greenhouse produced larger early yields in the field, but there was no effect of N or P level applied in the greenhouse on total yield. Four- and 5-week-old plants produced greatest total yields.
Three onion (Allium cepa L.) cultivar transplants were grown in the greenhouse in 200-cell plastic trays with one, two, or three plants per cell; at 75, 150, or 225 ppm N; and for 8, 10, or 12 weeks. Increasing the number of plants per cell resulted in smaller seedlings at transplanting and reduced time to maturity in the field by 1 week. Two and three plants per cell yielded more bulbs ≥76 mm in diameter, but one plant per cell had the highest percentage of bulbs ≥102 mm in diameter. Older seedlings and higher N applications produced larger plants at transplant and larger bulbs at harvest. Increasing N applications reduced maturation time slightly. Bulb fresh weight at harvest and yield of bulbs ≥76 mm in diameter were highest with 10- and 12-week-old transplants, and at 150 and 225 ppm N.
Celery (Apium graveolens L.) seeds germinated at 10°C for 14 days produced shorter and more uniform radicles (0– mm) than seeds germinated for 8 days at 24° (0–10 mm). Removal of seed leachates improved the germination of celery seeds in the light. Celery seeds germinated at 10° prior to sowing emerged faster, and produced more uniform plants than those not pregermihated, and were not thermodormant when incubated at 32°.
Pickling cucumbers (Cucumis sativus L.) for machine harvest were interplanted with barley (Hordeum vulgare L.), oat (Avena sativa L.), rye (Secale cereale L.), sorghum-sudan (Sorghum vulgare L.), or wheat (Triticum aestivum L.). Cover crops 3 to 5 (7.6 to 12.7 cm) or 6 to 10 inches (15.2 to 25.4 cm) tall were killed with sethoxydim. Cover crops seeded at ≈12 seeds/ft2 (129 seeds/m2) provided protection from wind erosion and minimal crop competition. Additional nitrogen to obtain maximum yield was required when small grain cover crops were interplanted with cucumbers. Barley emerged rapidly, grew upright, and was killed easily with sethoxydim, making it ideal for interplanting. All cover crops caused some cucumber yield reduction under adverse growing conditions.