The GRASS (V. 4.0) geographical information system (GIS) was used to test the hypothesis that pheromone trap based predictions of Helicoverpa zea (Boddie) damage in processed sweet corn could be improved by considering spatial patterns of corn plantings and wind blocking features around the trap. Wind blocking features include: tree rows, wooded areas, large buildings close to the trap, and abrupt hillsides. Pheromone traps were monitored at 29 and 30 sites in 1990 and 1991. Corn development through the year and damage levels at harvest (percent infestation) were also recorded for these locations. Maps of all corn plantings and wind blocking features within 2.5 kilometers of the trap were created, digitized, and entered into the GIS for each site. A stepwise regression analysis considering 18 spatial and two non-spatial variables resulted in a highly significant (P<0.001) four variable regression model with an R�� of 0.82. Spatial input variables used in this model included the total number of hectares of corn within 2.0 kilometers of the trap as well as the average distance to wind blocking features on the north side of the trap. The non-spatial variables used were cumulative trap catch and date of first silk. A dynamic simulation model was also created. This was designed to filter from the trap catch those moths coming from plantings outside of the trapped planting. This model functioned by creating map surfaces in the GIS showing for each day the relative contribution to catch for each location around the trap. This map surface was the product for each location of relative moth population levels and the likeliness that a moth positioned there would be captured by the trap. The modified cumulative trap catch was expected to correlate more strongly to damage levels than the unmodified trap catch, but no run of the model produced a significant improvement in the correlation. In the process of collecting data for this project, circumstantial evidence was obtained which indicated that high synchrony between valley-wide moth catch levels and valley-wide timings of silking in corn could be used as an indicator of high damage years. / Graduation date: 1994

During the springs of 1988 1989, experiments were conducted to determine effective methods of controlling damage by ring-necked pheasants (Phasianus coichicus) to sprouting corn in southwestern Idaho. Plot evaluations (1988) failed to demonstrate the ability of Miller Hot Sauce Animal Repellent, Isotox Seed Treater (F), provision of alternate food, and bird scaring reflective tape to reduce damage. When evaluated using entire production fields for replicates (1989) firecrackers on fuse rope, bird scaring reflective tape, hawk-kites, and provision of alternate food all significantly reduced the number of seedlings disturbed by ring-necked pheasants. No treatment in either experiment significantly increased the number of surviving corn seedlings. Fields were damaged from germination until the average sprout height exceeded 10 cm, but damage was greatest (69%) when sprouts were less than 5 cm tall. Management recommendations to avert damage include establishing treatments prior to the onset of damage and avoiding early planting dates. / Graduation date: 1991

No description available.

Studies of the life history and habits of Diabrotica longicornis (Say), a new pest of corn in Quebec, were undertaken in the field and in the laboratory. Seasonal activity and habits were established by monitoring life stages in the field during the years 1979, 1980 and 1981. The threshold temperature for development of NCR eggs was estimated at 9.7(DEGREES)C. The mean thermal constant for first hatching in the laboratory was 326 degree days above 9.7(DEGREES)C. Eclosion occurred in the field when average soil temperature conditions at the 5 - 10 cm depth reached 331 - 334 degree days. / Pupation occurred in the soil from late June to early July. Adults emerged from mid-July to August, and oviposition occurred during the same period. Oviposition preferences of NCR beetles were studied in relation to local soil types, soil moisture, and soil surface conditions, both in the laboratory and in the field under free choice conditions. In both cases, a clear preference was shown for moist, cracked, clay soil. / The behaviour of adults held under controlled environmental conditions (12L:12D diel light cycle, 23 (+OR-) 2(DEGREES)C temperature, 60 - 80 per cent RH) was investigated, and emergence, locomotor activity and sexual behaviour were recorded. The duration of larval stages reared in the laboratory on natural diets were compared with those for field-collected larvae. Natural enemies and mortality factors for the species were investigated in the field. A simple method for rearing NCR in the laboratory was developed.

No description available.

Horizontal distribution of Diabrotica longicornis (Say) eggs around plants was random in three Quebec cornfields. Vertically, 72% and 24% eggs occurred in the surface 10 cm soil before and after fall plowing, respectively. A 5 x 10 cm x 15 cm (deep) sampling unit was appropriate for estimating egg populations before plowing. Thereafter, 20 cm depth was needed. Larvae and pupae were concentrated around the root system and a soil quadrat 20 x 20 cm x 10 cm (deep) was an easily reproducible sampling unit. Direct counting on corn plants in early morning was the most efficient method for adult sampling. Sample sizes for all stages were calculated for different precision levels. Spatial distribution of eggs and larval field populations were contagious, and a stratified random sampling is appropriate for density estimation. Spatial distribution of adults changed with corn phenology. Average mortality of overwintering eggs was 66% and of spring larvae 89%. The field population density of beetles did not change significantly during 1979-82.

Maize (Zea mays L.) is one of the most important crops in South Africa that is cultivated for food, feed and as a cash crop. Maize in the Eastern Cape is typically grown for consumption and the Province is one of the least producers owing to small landholdings, poor production conditions and pests. This study investigated: (i) the different maize cropping systems smallholder farmers practice in the Eastern Cape (EC), (ii) the major maize insect pests within the identified cropping systems, (iii) the perceptions of Eastern Cape smallholder maize farmers on the effects of insect pests, and (iv) the effects of crop residues on insect pests’ population dynamics. Four major cropping systems namely: maize sole cropping without rotations by government sponsored farmers (GCP) (94 percent), maize intercropping without rotations by independent farmers (IF) (79 percent), maize sole cropping without rotations by IF (67 percent) and maize intercropping without rotations by GCP (61 percent) were identified. The choice of a cropping system by the smallholder farmers was significantly influenced by source of sponsorship, the difference in their district localities, tenure system, availability of inputs and farming equipment, percentage of farmland farmers allocate to maize, maize varieties, farming experience, fallow operations and access to irrigation facilities. The major constraints faced by the farmers in maize production are the attack by insect pests, weeds competition, drought, the lack of fencing around the fields and destruction by mammals. The major insect pests identified were stalk borers (Busseola fusca, Chilo partellus), cutworms (Agrotis spp.), aphids (Rhopalosiphum maidis), bollworms (Helicoverpa armigera) and weevils (Sitophylus spp.). The most popular control measures employed were the use of GM maize and pesticides. Results from the field trial showed that field crickets were the major ground dwelling insect pests observed followed by bollworms and cutworms. However, there were no significant influence of residue retention on the insects’ diversity indices, richness, and evenness. Above ground insects sampling revealed the domination by four major insects namely, cutworms, maize stalk borer, bollworms, and spotted stalk borer. Residue management significantly influenced the infestation by spotted stalk borer only on maize plots. However, the general trend was that there was less infestation by the insects in plots where residues were retained than the ones with residue removed. Results from the study indicate that government sponsorship is significantly influencing the maize cropping systems of the smallholder farmers of the Eastern Cape.

No description available.

No description available.

No description available.