Phyllotreta cruciferae is an important insect pest of spring-planted Brassica crops, especially during the seedling stage. To determine the effect of early season P. cruciferae infestation on seed yield, 10 genotypes from each of two canola species (Brassica napus L. and Brassica rapa L.) and two mustard species (Brassica juncea L. and Sinapis alba L.) were grown in 2 yr under three different P. cruciferae treatments: (1) no insecticide control; (2) foliar applications of endosulfan; and (3) carbofuran with seed at planting plus foliar application of carbaryl. Averaged over 10 genotypes, B. rapa showed most visible P. cruciferae injury and showed greatest yield reduction without insecticide application. Mustard species (S. alba and B. juncea) showed least visible injury and higher yield without insecticide compared with canola species (B. napus and B. rapa). Indeed, average seed yield of S. alba without insecticide was higher than either B. napus or B. rapa with most effective P. cruciferae control. Significant variation occurred within each species. A number of lines from B. napus, B. juncea, anid S. alba showed less feeding injury and yield reduction as a result of P. cruciferae infestation compared with other lines from the same species examined, thus having potential genetic background for developing resistant cultivars.

Resistance of canola-quality cultivars of yellow mustard,Sinapis alba L., to the cabbage seedpod weevil, Ceutorhynchus obstrictus (Marsham) J

In 1995 a study was conducted in split-split-plot design to determine the effect of single, double, and equilateral planting configurations with a single and double recommended rate of fertilizer (NPK), would have on the yield of four sweetpotato cultivars. TU-1892, Jewel, TU-82-155, and Georgia Jet were planted on a raised shaped bed 2 ft wide. Fertilizer was banded in the center of the bed and plants were then placed 6 inches away on both sides of this band for the double and equilateral configurations and on one side for the single configuration. Plants were spaced 12 inches apart within rows and the rate of fertilizer used for both single and double rows was the recommended rate for single rows. All plots were side dressed with an additional 80 lbs/acre of K at the time of flowering. Marketable yield data showed that by doubling the recommended rate of fertilizer yield increased for all cultivars which ranged from 26%-41% for single, 35%-88% for double, and 64%-104% for equilateral configurations, respectively. The results also indicated that net returns for TU-1892 was 217%, Jewel 136%, TU-82-155 203%, and Georgia-Jet 171%, for double and equilateral configurations, respectively, when the rate of fertilizer was doubled.

The effect of various mulch colors (black, yellow, red, blue, white, and aluminum) on growth and development of `Vates' collards was evaluated in Fall 1996 at the E.V. Smith Research Center in Shorter, Ala. Black polyethylene mulch was installed onto raised, fumigated beds, then sprayed with a 1: 2 (v/v) mixture of exterior oil-based enamel paint to paint thinner with one of the five mulch colors listed. Five-week-old plants were transplanted into beds. Beginning two weeks after transplanting and continuing every other week thereafter, heads were harvested to determine head fresh weight and dry weight. Hourly soil temperatures at 10 cm soil depth were recorded and growing degree days (GDDs) with a base temperature of 4.4 °C were calculated. At two weeks after transplanting, average head fresh and dry weight were highest for the aluminum-colored treatment with head fresh (24.7 and 12.3 g, respectively) and dry weights (2.7 and 1.3 g, respectively) twice that of the yellow treatment (P ≤ 0.05). By four weeks after transplanting and up through the final harvest, marketable yield and average head fresh weights did not differ among the treatments (17,900 kg/ha, 1.4 kg per head, respectively). The red and black mulch treatments accumulated more GDDs than the other treatments, but total marketable yields did not differ among any treatments.

No abstract