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Dispersal Gradients And Deposition Efficiency Of Venturia Inaequalis Ascospores And Their Relationship To Lesion Densities (Apple Scab Disease, Spore Dispersal, Trapping), Jonathan David Kaplan

Doctoral Dissertations

The airborne dispersal of Venturia inaequalis ascospores and Lycopodium sp spores from a point source was examined in an apple orchard. Twenty-five volumetric spore traps were constructed, and a system developed that governed intervals of trap operation by leaf wetness. The estimated inoculum density was equal to several unsprayed trees, much greater than inoculum densities in well-managed commercial orchards.

Dispersal gradients were analyzed using the equation Y = a + bX(,1) + cX(,1)('2) + dX(,1)('3) + eX(,2), where Y is the log of spores trapped, X(,1) is the log of distance from the source, and X(,2) is a constant to …

Characterization Of Sod-Induced Alfalfa Seedling Injury (Allelopathy, Anaerobiosis), David James Lang

Doctoral Dissertations

Field and greenhouse studies were conducted to examine the seedling vigor of sod-sown alfalfa (Medicago sativa L.).

Seedlings grown in tilled soil had more dry matter, were taller, and had longer internodes than seedlings in sod. Node number and plant density were reduced in some experiments. Seedling vigor was not hindered by physical impairment of seed germination, inadequate soil fertility, weed or sod competition, soil moisture, herbicide injury, or predators.

Time interval between tillage of sod and planting date affected seedling vigor. Seedlings growing in sod tilled the previous fall had higher yields than those sown in freshly tilled sod …