A significant portion of harvested produce never reaches the consumer due to, postharvest diseases. Various chemicals have been used to reduce the incidence of postharvest diseases. Many of these materials have been removed from the market in recent years due to economic, environmental, or health concerns. Although somewhat limited in the range of diseases controlled, chlorination is effective when combined with proper postharvest handling practices. Additionally, it is a relatively inexpensive postharvest disease control method that poses little threat to health or the environment. The proper use of chlorination in the management of postharvest diseases in fresh fruits and vegetables is discussed.
M.D. Boyette, D.F. Ritchie, S.J. Carballo, S.M. Blankenship, and D.C. Sanders
Biological Control of Plant Diseases. S.B. Chincholkar and K.G. Mukerji (eds.). 2007. The Haworth Press, Inc., Binghamton, NY. 426 pp. plus index; 17 tables and 26 black-and-white photographs and illustrations; 6-inch × 8.35-inch format. ISBN
Harry A.J. Hoitink, Alex G. Stone, David Y. Han, Weidzheng Zhang, and Warren A. Dick
Compost offers the potential to suppress root rots and vascular wilts caused by soilborne plant pathogens, as well as plant diseases affecting aerial plant parts. Many factors affect the degree of control obtained. They include the decomposition level (stability) of the compost, the types of microorganisms colonizing the organic matter after peak heating of the compost, plant nutrients released by the compost (fertility), its salinity, loading rates, and other factors. Biocontrol agents in composts induce suppression through various mechanisms, including competition, antibiosis, hyperparasitism, and the induction of systemic resistance in the plant (roots as well as foliage) to pathogens. Examples of each of the effects are reviewed.
Liming Chen, Matthew Wallhead, Michael Reding, Leona Horst, and Heping Zhu
In commercial fruit production in the midwestern United States, producers usually employ integrated pest management (IPM) to control a variety of insect and disease pests ( Beckerman, 2018 ). IPM tactics include removing leaf litter and pruning out
Nicolas Tremblay, Tarif Charbaji, Francois Fournier, and Odile Carisse
Scientific literature contains several examples of disease development influenced by fertilization practices. A set of data collected by the «Scouting and Research Network, South of Montreal Area» and consisting of disease and tissue analysis data on carrot and onion crops was made available for principal component analysis. It was hypothesized from the analysis that high N tissue levels would reduce Cercospora carotae and Botrytis squamosa importance on carrot and onion leaves, respectively. In a controlled environment study, Cercospora spots were inversely related to urea levels sprayed on carrot leaves although urea had no influence on plant growth. In a field study with onion, however, urea sprayed at 10 kg/ha, alone or in combination with a fungicide, had no effect either on Botrytis or on maturation or yield. With these mixed results, more research seems needed to assess the potential of nutrient sprays in reducing pesticide use.
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.
W.P. Cowgill Jr., M.H. Maletta, and S.A. Johnston
Two disease forecasting systems - FAST, Pennsylvania State University and CUFAST, Cornell University - were used to generate spray schedules for controlling Alternaria solani Ell. and Mart. on `Celebrity' tomato (Lycopersicon esculentum Mill.) at The Rutgers Snyder Research and Extension Farm in Northwest New Jersey. Disease control was compared to that obtained following standard weekly spray schedules. Chlorothalonil, 1.5 lb/A, was used for disease control for all treatments. Disease ratings of the FAST and CUFAST plots were significantly lower than that of the unsprayed control and were not significantly different from the plots sprayed according to standard spray schedules. A total of 10 fungicide applications were made following FAST recommendations; 7 applications were made following CUFAST recommendations; 13-15 applications were made following standard recommended schedules. Using CUFAST resulted in an estimated $200 per acre savings in spray costs. Chemical name used: tetrachloroisophtalonitrile (chlorothalonil).
J.B. Magee, B.J. Smith, and Agnes Rimando
Control of muscadine diseases is necessary to minimize yield loss and is especially important for highest quality fresh-market berries. In a systematic disease control spray program, four fungicides registered for grapes were applied sequentially at 10- to 20-day intervals from early bloom until just before harvest to five muscadine cultivars. Objectives of the study were to: 1) determine the effects of the spray schedule on foliage and berry diseases; and 2) study the relationship between disease incidence and resveratrol content of the berries. Resveratrol, a phytoalexin, has shown potential value in prevention and treatment of cardiovascular disease and certain cancer processes. Foliar diseases were rated visually twice during the season. Berry disease ratings were made at harvest. All fungal foliage and berry diseases were significantly reduced by fungicide treatments. Resveratrol was determined separately on berry skins, seed and pulp/juice by gas chromatography/mass spectroscopy (GC/MS). Overall, resveratrol levels in berry skins from unsprayed vines were much higher than those of sprayed vines. Concentrations varied by cultivar and within cultivar by treatment. The relationship between resveratrol concentration in skins and total disease score or scores of specific diseases was not established. Seed resveratrol concentrations differed by cultivar but were not affected by the fungicide treatments. Resveratrol concentration of seed was lower than that of skins. Accumulation of resveratrol in juice/pulp was much lower than in skins and seeds.
R.S. Roark, B.K. Behe, and K.L. Bowen
Five antitranspirant materials, a horticultural oil, the fungicide chlorothalonil, and an untreated control were applied to rose plots using one of four application schedules. After 12 weeks, treatments were evaluated for their effectiveness in control of blackspot. Disease (P=0.0022) and defoliation (P=0.0008) showed significant treatment differences, while vigor and flowering were unchanged. Two antitranspirants, Stressguard 0.05% applied every 2 weeks and NuFilm17 1% alternated with chlorothalonil around rain events, gave similar disease control to weekly chlorothalonil applications. One antitranspirant, Vapor Gard, 1 % alternated with chlorothalonil around rain events, gave similar defoliation control to weekly chlorothalonil applications. These results indicate that blackspot disease can be effectively managed with fewer applications of chlorothalonil.
Mary C. Koelsch and Janet C. Cole
Vinca minor production in Oklahoma nurseries has declined in recent years due to foliar diseases. A study was conducted to determine whether several labeled and experimental fungicides control these foliar diseases in Vinca minor `Bowles'. This study was conducted outdoors under unusually mild and humid conditions, which were conducive factors for disease symptoms to occur throughout the season. Plants were sprayed at weekly intervals with the fungicides propiconazole (0.95 ml/liter), thiophanate methyl (1.58 ml/liter), thiophanate methyl/mancozeb (1.79 g/liter), triforine (3.95 ml/liter), CC 17461 (3.95 ml/liter), CGA 173506 (0.47/liter), or SAN 619 (0.79 ml/liter). Thiophanate methyl/mancozeb was the most effective of all chemicals at decreasing foliar dieback; however, no chemical completely controlled the disease symptoms throughout the season. Dry weights of plants treated with thiophanate methyl/mancozeb were greater at the end of the season than those of plants receiving the other fungicidal treatments.