Search Results
Abstract
Significant differences (P = 0.05) in fruit infestation by codling moth larvae were found when fruit of 5 apple selections, with different levels of leaf pubescence, were evaluated. No differences in entry into fruit were found when larvae were placed on the relatively glabrous upper leaf surface. Selections having a pubescent lower leaf surface had significantly (P < 0.05) reduced numbers of entries. Females allowed to oviposit freely on fruit and leaves preferred to oviposit on the glabrous upper leaf surface. In all but one selection, more eggs were laid on the leaves than on the fruit. About 70% of larval entries were found in the midsection of the fruit, with 14% and 15% occurring at the calyx and stem ends, respectively. Larval entry was increased on the side of the fruit closest to the light source. Leaf pubescence seems to be a factor in 1st brood codling moth preference of apple cultivars.
Abstract
Response of hybrid summer squash (Cucurbita pepo L.) cvs. Seneca Zucchini and Zucchini Elite to trickle irrigation and black plastic mulch was evaluated in field studies conducted on a southwestern Indiana loamy sand soil during 1982 and 1983. Trickle irrigation and plastic mulch each increased plant growth, early bloom, and yield. Trickle irrigation reduced percentage of culls. Plant growth was correlated negatively with days to bloom after planting. Days to bloom were correlated negatively with yield; the early-blooming plants tending to yield more than the late-blooming plants. Significantly higher yields are possible with current cultivars using trickle irrigation and plastic mulch.
Abstract
Twenty-eight apple selections exhibiting different levels of powdery mildew resistance, based on greenhouse and field ratings from other investigations at other locations, were evaluated as grafts in the greenhouse for European red mite survival and development. Although we found selections HAR5T8, HAR8T140, HCR9T48, HCR14T149, OR48T70, and TSR14T146 to have a significantly (P = 0.05, 80 df) higher powdery mildew rating than NY55140-19, at one or more European red mite counts the other 22 selections did not show similar differences. Only selection HAR5T142 had significantly higher (P = 0.05, 80 df) mite counts relative to HCR21T200. The absence of a relationship between powdery mildew and European red mite infestations in apple was demonstrated through the lack of significant correlation between the levels of infestation by these 2 pests.
Abstract
Significant differences in mean leaf hair density values were found between strains of ‘Delicious’ apple (Malus domestica Borkh.) within locations (states). There were also location differences among strains common to more than one location (state). Ranking of strains according to the amount of pubescence present appeared relatively consistent between states.
Abstract
“No choice” procedures were established to complement “free choice” procedures for determining resistance of apple fruit to 4 insect pests. ‘Starking Delicious’ was more resistant to damage by apple maggot, Rhagoletis pomonella (Walsh) than ‘Jonathan’ or ‘Golden Delicious’. There were no differences in damage to ‘Jonathan.’ ‘Golden Delicious’ and ‘Starking Delicious’ by plum curculio, Conotrachelus nenuphar (Herbst) or redbanded leafroller, Argyrotaenia velutinana (Walker). The resistance of some apple scab resistant selections to these insects and codling moth, Laspeyresia pomonella (L.) previously determined in a “free choice” test was confirmed in this “no choice” test.
Abstract
Methods of evaluating resistance of apple fruit to 4 insect pests were established by modifying existing rearing procedures. When ‘Jonathan’ was used as the check cultivar and an adjustment was made for variation between trays among checks, it was possible to separate selections that were significantly more resistant from randomly selected samples of apple genotypes. We found 9.7 22.9, 32.3, and 17.0% of the selections tested against the codling moth, Laspeyresia pomonella (L.), plum curculio, Conotrachelus nenuphar (Herbst), apple maggot, Rhagoletis pomonella (Walsh), and redbanded leafroller, Argyrotaenia velutinana (Walker), respectively, had significantly less damage than the check.
Abstract
Selections of apple (Malus domestica Borkh.) from the cooperative breeding program for disease resistance were evaluated in 3 tests for resistance to the European red mite. Field-collected detached leaves used to determine infestations of motile mites throughout the growing season, dormant twigs used to determine overwintering eggs, and in situ examination of artificially infested leaves of greenhouse-growing whip grafts indicated good sources of resistance. Selections with less hairy leaves supported fewer mites than selections with an abundance of hairs. Selection PRI 1677-2, 1957-1, 2023-1, 2175-7 and 2175-25 show consistently good resistance to the European red mite warranting their use in vegetative propagation or use as parents in breeding for resistance.
Abstract
American elm (Ulmus americana L.) and American sycamore (Platanus occidentalis L.) trees were injected in May or June 1974 and 1975 with water solutions of 1,2-dihydro-3,6-pyridazinedione (Maleic hydrazide, MH) and butanedioic acid mono-(2,2-dimethylhydrazide (daminozide). Measurements in 1977 showed sprout length to be significantly reduced by both chemicals applied in 1974. Of the 1975 treatments, only MH-treated sycamore still showed significant sprout length reduction 3 growing seasons after injection. Between April and June 1977, MH and the sodium sait of 2,3:4,6-bis-0-(1-methylethylidene)-α-L-xylo-2-hexulofuranosonic acid (dikegulac) were injected into the trunks of previously topped American sycamore, silver maple (Acer saccharinum L.), red oak (Querem rubra L.), shamel ash (Fraxinus uhdei (Wenz.)Lingelsh), and eucalyptus (Eucalyptus globulus Labill.). Both chemicals significantly reduced regrowth, but high concentrations were generally more effective than were low concentrations of the same chemical. However, high concentrations of dikegulac were likely to cause unfavorable foliar appearance, including leaf distortion and dieback. Regrowth control was generally similar for a species treated with the same chemical at different geographical locations. Average injection cost for a single treatment is estimated at $2 to $3 per tree.
Abstract
Seeds of cabbage (Brassica oleracea (Capitata group) contain 10-fold more glucosinolates than do cabbage heads (dry basis). Seeds give rise to relatively greater amounts of goitrin and lesser amounts of SCN ion than do heads. In spite of these differences, seeds of 50 cabbage cultivars are shown to have fair predictive value for glucosinolate patterns in the corresponding heads.
Abstract
Selections of apple (Malus domestica Borkh.) of known parentage were exposed in a greenhouse to artificial infestations of European red mite. The clones PRI 95356, N.J. 70, PRI 123056, and PRI 159155 and ‘Vista Bella9, were the least preferred (P = 5%); mite counts per leaf and per cm2 of leaf area were highly correlated even though the leaf area varied within and between selections. There was no evidence that any parent in the pedigrees contributed to ERM resistance based on an analysis of the association of mite numbers for the 4th and 5th week after infestation and the expected frequency of genetic contribution from various parents in the pedigree.