Undamaged Plant Research Articles

Black Cutworm Control, 1989

Abstract Performance of granular and liquid insecticides against BCW was evaluated with artificial infestations at the Rosemount Experiment Station, Rosemount, MN. Treatment plots, each measuring 4 rows (30-inch spacing) × 50 ft, were established in corn planted on 2 Jun. Treatments were arranged in a randomized complete block design with 4 replications. Granular insecticides were applied in a 7-inch band ahead of the presswheel or in furrow at planting with modified Noble applicators mounted on a John Deere 7100 MaxiMerge planter. When corn reached the 2-leaf stage a central portion of each plot (2 rows × 15 ft) was enclosed by an aluminum barrier buried 3-4 inches into the soil that projected 4 to 5 inches above soil level. Plant population within the barriers was thinned to 23,900 plants/acre. Liquid insecticides were broadcast on 15 Jun am using a CO2-powered backpack sprayer calibrated to deliver 21 gal/acre at 25 psi through 8002 nozzles. During application, air temperature averaged 77°F and winds ranged from still to 2 mph. Each plot was infested with a mixture of 40 third and fourth instar black cutwork larvae on the evening of 15 Jun and early morning of 16 Jun. Plots were examined every 2-3 d for leaf feeding and cutting. Cut plants were marked with a plastic stake to avoid misses or recounts as undamaged plant on later visits. On 27 Jun (11 d after infestation), each plot was censused with the number of injured plants and dead plants recorded. Before analysis, percentage data were subjected to an arcsine transformation.

Coping with Victimization by Technological Disaster

Technological catastrophes, defined as mishaps involving breakdown in human‐made systems, appear to differ in the nature of threats that they pose. Coping with chronic stress associated with these events was examined by considering response to the Three Mile Island nuclear accident. Using the Ways of Coping Inventory (Folkman & Lazarus, 1980), use of emotional regulation, problem‐oriented coping, and the assumption of responsibility or blame for problems associated with living near the damaged plant were considered. Patterns of response at TMI were compared to those of a control group, consisting of people living near an undamaged nuclear plant more than 100 miles from TMI. Stress was assessed by making simultaneous measurements of symptom reporting, task performance, and urinary catecholamines (epinephrine and norepinephrine). Findings suggested that both emotionally‐focused coping and self‐blame were associated with less stress than were problem‐focused coping and denial. Further, emotional regulation and assumption of responsibility for encountered difficulty were related to one another and to perceived control as well. This suggested that a control‐oriented coping style, in which the perception of control is actively created or maintained, can be effective in reducing distress associated with technological catastrophes.

Voters reject reopening undamaged TMI plant

Voters reject reopening undamaged TMI plant

Further investigations of the toxicity of fusicoccins

Fusicoccin is a non-specific phytotoxin. Variation in the response of the 75 plant species tested parallels their natural resistance to desiccation. Fusicoccin is effective when supplied via the sap stream but the wilt it produces is not caused by interruption of vascular flow. It penetrates undamaged plant surfaces very slowly. Fusicoccin, at high concentration, inhibits growth of seedlings in submerged culture but the effects disappear on transfer to fusicoccin-free media. The compound itself does not cause death of the cells and it does not destroy their semipermeability, as shown by the wilt's being reversible. Fusicoccin increases the susceptibility of a tissue to death by desiccation, and its precise site and mode of action remain obscure. Ophiobolins A and B destroy cell semi-permiability. Although they bear a close structural similarity to the fusicoccins the two groups have different modes of action. Progressive de-acetylation of fusicoccin reduces the degree of physiological activity as a wilting agent, but tomato shoots showed a novel response, involving an increase of fresh weight, after taking up small amounts of desacetyl-desisopentenyl fusicoccin. Some proposed mechanisms concerning the mode of action of fusicoccins are discussed.

Effect of Aphid Infestation on the Coumestrol Content of Alfalfa Varieties Differing in Aphid Resistance1

The effects of pea aphid and spotted alfalfa aphid infestations on the coumestrol content of three alfalfa (Medicago sativa L.) varieties and one alfalfa synthetic were determined in plant growth chambers. The alfalfas tested ranged from very susceptible to highly resistant to both aphid species. Coumestrol from aphid‐damaged tissue was identified by chromatography and ultraviolet spectroscopy. Aphid‐damaged portions of all varieties contained elevated coumestrol levels. Undamaged plant tissue and uninfested plants generally had less than 1 ppm coumestrol. The more resistant varieties accumulated less coumestrol than the susceptible variety ‘Vernal.’ Selection in alfalfa for aphid resistance can be expected to reduce the accumulation of coumestrol which results fiom aphid damage.

Sources of the Lactic Acid Bacteria Occurring in Silage

SummaryLactobacilli, pediococci and leuconostocs were found to be scarce on living undamaged plant tissue. They were not found by direct plating of intact portions of the inflorescence or seed of any plant examined, but they were detected on foliage damaged by insects, on sheaths at the base of grasses and on withered blades of grass. The numbers of lactic acid bacteria on plant material increased during the harvesting and ensiling operations. Many organisms were recovered from the mechanical equipment and the hand implements used during harvesting of the crop.