The effect of BA on ‘Redchief strawberry (Fragaria × ananassa Duch.) growth and yield was evaluated. During the summer of row establishment (1982), matted row plots were sprayed to drip with BA at 0, 50, 125, or 250 ppm on 1 July, 1 Aug., or 1 Sept. In 1983 and 1984, subplots were treated with BA at 0, 200, 250, or 300 ppm on 15 Sept., 1 Oct., or 15 Oct., or on all three dates at 250 ppm. Treatments applied in 1982 had no effect on crowns/m2, side branches/crown, total yield/plot, or mean fruit weight. However, increasing BA concentration significantly reduced mean crown dry weight. BA applied in Fall 1983 had no effect on total yield/plot though harvest distribution was altered. BA application on 1 Oct. significantly reduced early yields compared to the other dates of application. Although both single and multiple BA application reduced early yields compared to the control, three applications caused the largest reduction. Multiple application in 1984 significantly reduced mean fruit weight on early harvest dates. Visual observation and rating of plots indicated BA did increase flower number, but the extra flowers exhibited poor fruit set and did not significantly increase yield. Chemical names used: N-(phenymethyl)-1H-purin-6-amine (BA).
Apple growers in Kentucky normally control pests on a preventative schedule involving fifteen or more chemical applications annually. IPM technology designed to provide growers information about the threat of diseases and insects was used in a demonstration plot in a Daviess County orchard and in the U.K. research orchard, Princeton. The IPM systems used in Daviess County resulted in 6 less applications of pesticides than the traditional system, a savings of approximately $130 per acre. When compared to the traditional preventative spray schedule, the IPM treated apples showed no differences in fruit quality and in orchard diseases and insect infestations. The decreased pesticide use has the potential to reduce applicator exposure, residues on fruit, and the environmental impact of these chemicals. The results of this demonstration were shared with and received an enthusiastic response from growers, Extension personnel, students, consumers, and the news media. The project demonstrated the feasibility of using apple IPM by a Kentucky grower, and it provided students an insight into applied biology.
Simulated frost injury to ovaries at intervals after full bloom significantly increased fruit malformation, reduced fruit weight, and increased fruit drop in ‘Bartlett’, ‘Bosc’, and ‘Comice’ pear (Pyrus communis L.). Time of injury did not affect fruit weight and malformation in most cases, but did significantly affect fruit drop. Significant positive correlations were found between fruit weight and seed content, while negative correlations were found between fruit malformation and seed content for all cultivars.
Controlled freezing tests showed no hardiness differences between comparable floral developmental stages on weak and vigorous ‘Bartlett’ (Pyrus communis L.) pear trees. Bloom delay through evaporative cooling resulted in a loss of hardiness beyond that found earlier in the season on non-misted trees for similar stages of development, although a certain degree of frost protection was gained through bloom delay.
The response of ‘Hull Thornless’ blackberry (Rubus spp.) to annual applications of three N rates (0, 41, and 123 kg N/ha) and straw or wood chip mulch plus 41 kg N/ha was studied. Pruning weight per plant increased linearly with increasing N rate in 1986 and 1987 and with straw mulch in 1987. Plants mulched with wood chips had the largest mean cane cross-sectional area, while neither N rate or straw mulch had an affect. Number of lateral branches per cane was not affected by any treatment. Yield increased linearly with N rate. Plants that received straw mulch produced yields that were greater than or equal to the high N rate. Mean fruit weight increased in response to straw mulch and increasing N levels in 1986, but only to the straw mulch in 1987. The number of flowers per cane and per inflorescence increased with increasing N rate, but inflorescence number per cane and fruit set were not affected. As N rates increased, yield per square centimeter of cane basal cross-sectional area increased. Both mulches decreased inflorescence number per square centimeter of cane basal cross-sectional area, but did not influence any other components of yield. Mean cane cross-sectional area, lateral branches per cane, inflorescences per cane, flowers per inflorescence, and mean fruit weight were significantly and positively correlated with yield per plant in 1987. Averaged over years, as the fertilizer N rate increased, primocane foliar N content increased, P declined, and K, Ca, Mg, and Mn were not affected. Mulching had no effect on nutrient element content.
Three landscape fabrics, Magic Mat®, a heavy black plastic woven fabric with a fuzzy underside; Weed Mat®, a thin black plastic sheet with small holes; and Typar®, a dark gray spun bonded material, with and without a cover of organic oak bark mulch, were evaluated for weed control and ability of strawberry plant roots to establish through the fabrics over a 4-year period. Landscape fabrics reduced weed numbers for the first 3 years in comparison with the bare ground treatment. With few exceptions. the organic mulch did not improve the weed control capability of landscape fabrics. Fruit yield for the Weed Mat and Magic Mat treatments did not differ from the bare ground treatment, but was lower for the Typar treatment when averaged over organic mulch treatments. Fruit yield was higher where the organic mulch was used when averaged over all landscape fabric treatments. Fruit size was slightly larger for the bare ground and smallest for the Typar treatments during the first harvest season, but there was no difference in fruit size by the third year of harvest. Fruit size for the organic mulched plots was slightly larger than that for the unmulched plots the second year of harvest, but there was no difference for the first or third years. The number of strawberry runner plants that rooted and plant row vigor were greater for the Weed Mat, Magic Mat and plots without the landscape fabric than for the Typar plots, particularly in the second and third season. Rooting of runner plants and plant row vigor was better with organic mulch. Landscape fabric tended to reduce extent of rooting, especially in the first season, but it was improved by the application of organic mulch.
Freezing studies on ‘Bartlett’ pear (Pyrus communis L.) bouquets of buds, flowers, and small fruit showed injury increased with decreasing temperature, increasing developmental stage, and increasing duration of frost. At the minimum temperature, 30 and 60 minutes of frost exposure in all stages increased injury, however, in the small fruit stage injury at −2°C increased for up to 2 hours exposure. The effect of freezing rate was dependent on minimum temperature and dry florets were injured slightly more than florets misted just prior to freezing.
Although the interest in and production acreage of organic fruit and vegetables has grown in recent years, there are questions about the viability of perennial crops such as apple (Malus ×domestica) in an organic system in Kentucky because of the long, hot, and humid growing season. Thus, the objective of this project was to assess the severity of the challenges to organic apple production in Kentucky. A high-density, organic apple orchard was established in 2007 in the University of Kentucky Horticultural Research Farm in Lexington. The orchard of apple scab (Venturia inaequalis)–resistant ‘Redfree’, ‘Crimson Crisp’, and ‘Enterprise’ trees on ‘Budagovsky 9’ (B.9) rootstock, trained in a vertical axis system, was managed using organically certified techniques and materials for disease and insect control since its inception. Tree growth, tree and fruit injury from insect pests and diseases, and yield over the period 2011–13 were studied. Periodic, shallow cultivation kept the ground beneath the trees free of vegetation once the lower limbs were pulled up and away from the path of the equipment. Vole (Microtus sp.) damage was a continuing problem despite the use of trunk guards and cultivation to remove habitat around the trees. Total fruit yield ranged from 1.2 to 8.1 kg/tree across years and cultivars, with the marketable proportion of the total yield averaging 68% for Redfree and 43% for Crimson Crisp and Enterprise over the 3-year period. The unmarketable fruit exhibited a high incidence of plum curculio (Conotrachelus nenuphar) damage, with generally less damage from codling moth (Cydia pomonella) and sooty blotch (Glosodes pomigena)/flyspeck (Schizathyrium pomi). In addition, in two of the three seasons, ‘Crimson Crisp’ and ‘Enterprise’, which were harvested at later calendar dates then ‘Redfree’, had significant levels of powdery mildew (Podosphaera leucotricha) injury, ‘Enterprise’ had significantly greater bitter rot (Glomerella cingulata), and ‘Crimson Crisp’ showed fruit and foliar damage from cedar apple rust (Gymnosporangium juniperi-virginianae). Because ‘Redfree’ was the only cultivar with an acceptable marketable proportion of the fruit crop, the use of early ripening disease-resistant apple cultivars may have the greatest potential for successful organic apple production in Kentucky and the surrounding region.