No abstract

The bacterial antagonists Pseudomonas fluorescens A506, Pantoea agglomerans C9-1, and Pantoea agglomerans E325 and preparations of Bacillus subtilis QST 713 containing bacterial endospores and lipopeptide metabolites were evaluated for efficacy in controlling fire blight in Michigan, New York, and Virginia. When examined individually, the biological control materials were not consistently effective in reducing blossom infection. The average reduction in blossom infection observed in experiments conducted between 2001 and 2007 was variable and ranged from 9.1 to 36.1%, while control with streptomycin was consistent and ranged from 59.0 to 67.3%. Incidence of blossom colonization by the bacterial antagonists was inconsistent, and <60% of stigmata had the antagonists present in 12 of 25 experiments. Consistent control of blossom infection was observed when the biological control materials were integrated into programs with streptomycin, resulting in a reduction of the number of streptomycin applications needed to yield similar levels of control. Our results indicate that the prospects for biological control of fire blight in the eastern United States are currently not high due to the variability in efficacy of existing biological control options.

In northern Virginia, over 80% of the apple crop is grown for processing. Many trees are propagated on vigorous rootstocks and require much pruning, especially in the tops. To reduce costs and labor needs, many growers prune every second or third year. When trees are not pruned, shading caused by growth in the current season or in nonpruned years is detrimental to pest control, fruit quality, and yield.Several plant growth regulators have been evaluated for their potential to reduce vegetative growth of tree fruits, thereby reducing pruning costs and improving fruit quality. Several reviews (Faust, 1984;Looney, 1983;Luckwill, 1970;Miller, 1988;Williams, 1984) dealing with many of these compounds indicate that most have several effects of greater commercial value than control of vegetative growth.The objectives of the experiments reported here were to evaluate the effects of prohexadione-calcium (3-oxido-4-propionyl-5-oxo-3cyclohexene-carboxylate), formulated as BAS-125 ("Apogee" ® ), on a) vegetative growth of apple and peach trees, b) fruit size and quality, and c) response to thinning chemicals. MATERIALS AND METHODSGeneral. Randomized complete-block designs were used in all experiments. Trees were blocked by location within rows, by rootstock, and/or by flower density rating. All experiments had six blocks except for Expts. 1, 4, 5, and 6. Trees were sprayed with either a low pressure hand-wand sprayer or a Swanson three-point-hitch airblast sprayer with both fans adjusted to one side, which doubled air output and increased nozzle numbers.In several experiments (Expts. 1-4), a 10-fruit sample was collected from each tree at harvest for quality evaluations, which included flesh firmness, soluble solids concentration, starch staining, percentage of red color, and incidence of water core. Flesh firmness of both peach and apple fruit was measured on two sides of each fruit with an Effegi penetrometer (model FT327; McCormick Fruit Tech, Yakima, Wash.) fitted with an 11.1-mm tip. Soluble solids concentration (SSC) was estimated with an Atago hand-held refractometer (model N1; McCormick Fruit Tech), utilizing a composite sample of juice resulting from penetrometer testing for each replicate of each treatment. Each apple fruit was cut in half transversely, and severity of water core was rated on a scale of 0 to 5 (0 = none, 5 = severe). Flesh starch was evaluated by dipping half of each apple in a solution of I 2 /KI for ≈15 s. The degree of staining was rated on a scale of 0 to 5 where 1 = staining of the entire cut surface and 5 = absence of starch (Poapst et al., 1959).In the dormant season (Expts. 1-4), average shoot length of the longest top two shoots, length of the five longest scaffold shoots, total length of shoots longer than 30 cm, weight and basal and terminal shoot diameters of these scaffold shoots, nodes/cm of the basal 40 cm, nodes/cm of the upper 30 cm of shoots, and time required to prune each tree, number of cuts/tree, and pruning weights/cm 2 trunk cross-sectional area (TCSA) per tree were recorded...

Sooty blotch and flyspeck (SBFS) fungi colonize the surface wax layer of the fruit of apple, pear, persimmon, banana, orange, papaya, and several other cultivated tree and vine crops. In addition to colonizing cultivated fruit crops, SBFS fungi also grow on the surfaces of stems, twigs, leaves, and fruit of a wide range of wild plants. The disease occurs worldwide in regions with moist growing seasons. SBFS is regarded as a serious disease by fruit growers and plant pathologists because it can cause substantial economic damage. The smudges and stipples of SBFS often result in downgrading of fruit from premium fresh-market grade to processing use. This review describes the major shifts that have occurred during the past decade in understanding the genetic diversity of the SBFS complex, clarifying its biogeography and environmental biology, and developing improved management strategies.