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Several factors, including pH and timing and number of applications, affect the efficacy of fosetyl-Al for controlling bacterial disease on ornamentals. Although pH may be a factor in the efficacy of fosetyl-Al for sensitive bacteria such as strains of Xanthomonas campestris pv. dieffenbachiae from Syngonium, sensitivity to pH alone cannot adequately explain the response of bacteria to exposure to fosetyl-Al in vitro. Disease control appears to be based on surface factors rather than chemical changes within the leaf tissue, since bacterial populations following leaf infiltration reach similar numbers whether plants are treated with fosetyl-Al or water

Percentage of blighted leaf aera decreased linearly as the rate of complete fertilizer(liquid 20:20:20 or slow-release 19:6:12) increased: Increased rates of either nitrogen or potassium were equally effective in reducing symptom expression. Plant response(number of leaves, height, and top quality) to increasing rates of complete fertilizer was generally described by a quadratic function, and good plant growth occurred over a wide range of fertilizer rates

CHASE, A. R., and D. E. MUNNECKE. 1980. Control of Acremonium wilt of Shasta daisy. Plant Disease 64:377-379. Shasta daisies (Chrysanthemum maximum) were propagated in vitro using shoot tips (0.5 mm long) from field-grown 'Killian' daisies infected with Acremonium strictum. Viable explants were assayed, and those free from internal fungal and bacterial contaminants were multiplied in vitro. Commercial fumigation of naturally infested fields (sandy loam soil) at the rate of 340 kg per hectare of a 2:1 mixture of methyl bromide and chloropicrin delayed reinfection of pathogen-free plants for as long as 6 mo. Acremonium wilt of Shasta daisy (Chrysanthemum maximum Ram.) was first reported in 1978 (2). Symptoms include vascular browning, chlorosis and necrosis of the lower leaves, wilting, stunting, and overall debilitation of the host. The causal agent, Acremonium strictum W. Gams (3), is a weak pathogen dependent on stress of the host for maximum development in the plant. Elimination of the fungus from the plant Present address of senior author: Agricultural Research Center-Apopka, Route No. 3, Box 580, Apopka, FL 32703.

Influence de la concentration en desinfectant de surface, des conditions de stockage des tissus, et de la duree d'exposition, sur l'isolement de C. spp. chez Ruhmora adiantiformis