Fresh Market Vegetable Production

Floating Row Covers Reduce Virus Transmission to Potato Seed Stock (1986)

Control of virus-vectoring insects, particularly aphids, is essential in production of potatoes for seed to exclude viruses such as potato virus Y, leaf roll, and net necrosis. Seed production fields are heavily treated with insecticides to prevent virus transmission, but control is often inadequate. Floating row covers may protect plants from attack by insect vectors, reducing the need for insecticides. Row covers might also increase yield through their effect on air and soil temperatures around the plants.

Response of Cucumber to Floating Row Covers and Herbicides (1986)

Crop protection with floating row covers interferes with tillage or other means of weed control. Therefore, herbicides or ground mulch are the likely means of weed control under covers. A successful weed control program depends on understanding the environmental and physiological interactions between the herbicide and other components of the cropping system. Results in 1983 with bunching onions (N. S. Mansour) indicated that paraquat residues on row covers might injure the subsequently emerging crop.

Lime and Gypsum Effects on Spring-Planted Onions (1986)

Fertilizer trials with overwintered onions at the North Willamette Station indicated a strong yield increase with application of lime, an increase with gypsum (calcium sulfate), and higher yields with ammonium sulfate rather than other N sources. The yield response to gypsum and ammonium sulfate indicated that when soil pH, N, P, and K are optimal, S may be the limiting element in onion production.

Nitrogen Rates and Phosphorus on Onions (1986)

Storage onions in western Oregon have been grown almost exclusively on lake bottom soils which are high in organic matter (more than 10%). Recently, production of onions on mineral or "upland" soils with low organic content and N availability has increased rapidly and now equals production on the organic soils. Response of onions to nitrogen rate and to applications of phosphorus and potassium on the mineral soils is not well understood.

Nitrogen Rates and Phosphorus on Carrots (1986)

Higher yields and improved root quality are essential for processing carrot growers to remain competitive. Nitrogen fertilizer applications range from 50 to 150 pounds N/acre with most between 50 and 80 pounds. More research is needed to clarify yield response to nitrogen, especially at higher rates, and the influence of N on such root characteristics as diameter, length, splitting, and rots. The response to N should be investigated at plant densities typically used for slicing and dicing.

Nitrogen Rate, Form, and Timing on Yield of Sweet Corn

Experiments at the North Willamette Experiment Station in 1979 and 1980 indicated that, for N applied as ammonium nitrate at 160 pounds N/acre, sweet corn yields were increased by delaying application of most of the N until the corn was 10 to 12 inches tall. These experiments were at fairly high levels of early season irrigation, and the lower yields when all N was applied at planting may have been caused by leaching of nitrate-N out of the root zone. In a trial in 1984, however, splitting the N application did not increase yield with ammonium nitrate as N source.

Lime and Fertilizer Effects on Overwintered Cauliflower (1986)

Overwintered cauliflower trials at the North Willamette Station and by growers have usually given acceptable yields and quality. However, yields of early varieties, and particularly in cold springs, have occasionally been disappointing. Since plant nutrient uptake is limited on cold soils, these low yields may have been caused by inadequate availability of P or other elements.

Early Autumn Cauliflower Variety Trial (1986)

Trials to evaluate the heat tolerance of cauliflower have been conducted at the North Willamette Station for several years. These trials were transplanted in late May for July harvest. The 1985 trial differed in that the varieties were transplanted in early July for late summer to early autumn harvest. As with the earlier trials, the major desired quality is the ability to withstand high temperatures without ricing or discoloration while producing a high density, moderately sized head.

Methods