Response of Cabbage to Insecticide Schedule, Plant Spacing, and Fertilizer Rates

Cabbage ( Brassica oleracea L. Capitata Group ‘Market Prize’) was grown in the spring (February to April) 1981 and fall-winter (October to January) 1981–82 with 2 insecticidal spray schedules conducted weekly and on demand; 2 in-row spacings, 23 and 38 cm; and 2 fertilizer rates, low (152N–53P–139K and 8 Mg kg/ha), and high (257N–99P–261K and 15 Mg kg/ha). Fenvalerate [Cyano (3-phenoxyphenyl) methyl-4-chloro-alpha-(1-methylethyl) benzeneacetate] at 0.112 kg a.i./ha was applied either weekly or when a threshold of 0.5 lepidopterous larval feeding injuries/plant was equalled or exceeded. With the weekly insecticide treatment, 12 and 10 sprays were applied, respectively, in the spring and fall, vs. 1 and 2 applications, respectively, for the 2 seasons in the demand plots. Insect damage ratings were lower in the weekly sprayed than in the demand plots; however, marketable yields (kg/ha) and average head size were not affected by spray schedules. In both seasons, marketable yields were greater at the 28 cm spacing than at 38 cm, whereas average head sizes were greater at 38 cm than at 23 cm. The high fertilizer rate increased head size in both seasons, but increased marketable yields only in the spring.