Plant height can be regulated by manipulation of day (DT) and night temperatures (NT). Traditionally, commercial flower crops are grown with a DT higher than the NT, which results in greater internode length than when the regimen is reversed. Because temperature manipulation is a popular height-control tool among growers, the influence of DT/NT regimens of 16/16, 19/19, 22/22, 16/19, 19/22, 16/22, 19/16, 22/19, and 22/16°C on foliage susceptibility to Botrytis cinerea was investigated. After a minimum 3-week temperature treatment, seed geraniums (Pelargonium × hortorum), petunias (Petunia × hybrida), and impatiens (Impatiens wallerana) were inoculated with 2.7 × 10 B. cinerea conidia per ml of water and incubated at 20°C for the duration of the experiment. When averaged over two experiments, the maximum proportion of geranium, petunia, and impatiens foliage infected was 81.5, 35.5, and 27.0%, respectively. The maximum proportion of leaves supporting sporulating B. cinerea was 59.5% for geraniums, 25.5% for petunias, and 5.5% for impatiens. Area under the disease progress curve data indicated that susceptibility of bedding plant foliage was not influenced by the difference in DT/NT regimens. Results suggest that growers that use higher NT than DT to limit plant height do not increase host susceptibility to B. cinerea. However, more rigorous disease management strategies are needed for production of seed geraniums than for petunias or impatiens.
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http://dx.doi.org/10.1094/PDIS.1999.83.6.589A | DOI Listing |
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