The influence of organic soil amendments (unamended control, composted dairy manure, or raw dairy manure) and weed treatments [critical period (CP) or no seed threshold (NST)] on diseases, growth parameters, yield, and postharvest quality was evaluated over 3 years in a transitional organic crop rotation of tomato, cabbage, clover, and wheat. More growth, yield, and postharvest quality parameters were affected by amendment treatments in cabbage than in tomato. Significant differences in yield among amendment treatments were found in 2001 and 2003 in cabbage, with higher marketable and total yields in amended vs. control plots. Soil management effects on cabbage varied annually, though amendments were required to maximize crop growth, as head weight, size, and volume and core volume of treatment plots exceeded the control plots in 2002 and 2003. Few differences were found between weed treatments, although in 2001 cabbage heads from the NST treatment were larger than heads from the CP treatment. Similar results were found in tomato in 2003. Also, the CP treatment had a higher Area Under the Disease Progress Curve than the NST treatment in tomato in 2003. Overall, disease pressure was highest in tomato in 2001. But disease levels within years were mostly unaffected by amendment treatments. In cabbage, disease was more common in 2002 than in 2003, although head rot was more prevalent in compost-amended plots in 2003 than in manure-amended or control plots. Tomato postharvest quality parameters were similar among amendment and weed treatments within each year. Soil amendment may enhance crop yield and quality in a transitional-organic system. Also, weed management strategy can alter weed populations and perhaps disease levels.
Annette Wszelaki, Sally Miller, Douglas Doohan, Karen Amisi, Brian McSpadden-Gardener, and Matthew Kleinhenz
Ji Heun Hong, Douglas J. Mills, C. Benjamin Coffman, James D. Anderson, Mary J. Camp, and Kenneth C. Gross
Experiments were conducted to compare changes in quality of slices of red tomato (Lycopersicon esculentum Mill., cv. Sunbeam) fruit from plants grown using black polyethylene or hairy vetch mulches under various foliar disease management systems including: no fungicide applications (NF), a disease forecasting model (Tom-Cast), and weekly fungicide applications (WF), during storage at 5 °C under a modified atmosphere. In this study, we used the fourth uniform slice from the stem end and analyzed for firmness, soluble solids content (SSC), titratable acidity (TA), pH, electrolyte leakage, molds, yeasts and occurrence of water-soaked areas. With both NF and Tom-Cast fungicide treatments, slices from tomato fruit grown with hairy vetch mulch showed greater firmness than those from tomato fruit grown with black polyethylene mulch after 12 d of storage. Ethylene production of slices from tomato fruit grown using hairy vetch mulch under Tom-Cast was about 1.5- and 5-fold higher than that of slices from tomato fruit grown under the WF and NF fungicide treatments after 12 d, respectively. Within each fungicide treatment, slices from tomato fruit grown using hairy vetch mulch showed less chilling injury (water-soaked areas) than those from tomatoes grown using black polyethylene mulch. The percentage of water-soaked areas for slices from tomato fruit grown using black polyethylene mulch under NF was over 7-fold that of slices from tomato fruit grown using hairy vetch under Tom-Cast. These results suggest that, under our conditions, fruit from plants grown using hairy vetch mulch may be more suitable for fresh-cut slices than those grown using black polyethylene mulch.
C.C. Reilly, B.W. Wood, and M.W. Hotchkiss
Zonate leaf spot (ZLS) [Cristulariella moricola (Hino) Redhead (C. pyramidalis Waterman and Marshall)] on pecan [Carya illinoinensis (Wangenh.) K. Koch.]—associated with unusually wet weather during June, July, and August—occurred across much of Georgia during Summer 1994. Scott–Knott cluster analysis indicated that 27 of 36 evaluated genotypes exhibited little or no field susceptibility to ZLS. `Moneymaker' exhibited the greatest susceptibility of all cultivars studied, with `Cape Fear', `Elliott', `Sumner', and `Sioux' segregating to exhibit moderate susceptibility. An evaluation of commercial orchards indicated susceptibility of major southeastern cultivars as `Desirable' < `Stuart' < `Schley' < `Moneymaker'. Control of ZLS in commercial orchards using standard fungicide spray strategies appeared to be generally ineffective.
Brenda Walsh, Stephanie S. Ikeda, and Greg J. Boland
Ronald K. Jones, Ann R. Chase, Melvin P. Garber, William G. Hudson, Jeffrey G. Norcini, and Kane Bondari
A national survey of the commercial ornamental industry was conducted to determine the current status of pest control including chemical and nonchemical disease control practices. The fungicides thiophanate methyl, chlorothalonil, mancozeb, and metalaxyl were used in the greatest quantity and by the largest percentage of growers. Metalaxyl was used in greenhouse and field operations by the highest percentage of growers, primarily to control root diseases but many growers reported using metalaxyl to control foliar disease. Overall, more fungicides were used in the field for foliar diseases, whereas almost equal amounts of fungicides were used for foliar and root diseases in the greenhouse.
D.E. Green II, J.D. Fry, J.C. Pair, and N.A. Tisserat
Mowing heights from 1.2 to 5.1 cm, five N sources with two application rates (74 and 148 kg N/ha per year), and seven preemergence herbicides were evaluated in field studies in Manhattan and Wichita, Kan., for their effect on large patch disease, caused by Rhizoctonia solani Kuhn AG 2-2, in zoysiagrass (Zoysia spp.). Turf mowed at 1.2 and 2.5 cm was more severely blighted than turf mowed at 4.5 or 5.1 cm. At all mowing heights, turf recovered by August or September. Disease severity was not influenced by N source, N rate, or preemergence herbicides.
Rohini Deshpande, D. P. Coyne, K. G. Hubbard, J. R. Steadman, E. P. Kerr, and Anne M. Parkhurst
The microclimate of Great Northern (GN) dry bean lines with diverse plant architecture was investigated in terms of white mold (WM) incidence and yield. A split-plot design was used with protected (3 weekly sprays of benomyl 0.9 KG HA-1 after flowering) and unprotected treatments as main-plots and GN lines as sub-plots in a WM nursery (1990, 1991). Canopy density, erectness, leaf area index, and plant characteristics were measured. `Starlight' (upright) and `Tara' (prostrate) were selected for detailed microclimate studies. An infrared thermometer, humidity sensor, and a thermistor were placed within the canopy at the advent of flowering. Leaf wetness and its duration were estimated by the leaf temperature in combination with air temperature and dewpoint temperature. `Starlight' showed later and shorter duration of leaf wetness, lower humidity, and WM and higher yield than `Tara'. Severe WM and reduced yields occurred also on all other susceptible entries with dense prostrate plant habits in the unprotected plots. Fractal analysis was done on the images of the canopy to quantify the light interception within the canopy.
William E. Klingeman, Gretchen V. Pettis, and S. Kristine Braman
these plants as new cultivars are introduced to commercial trade. Therefore, objectives of this study were to question landscape management professionals and categorize their perceptions about the potential for insect- or disease-resistant ornamental