Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/20/2005
Publication Date: 6/1/2006
Citation: Turechek, W., Peres, N., Werner, N. 2005. Pre- and post infection activity of pyraclostrobin for control of anthracnose fruit rot of strawberry caused by colletotrichum acutatum. Plant Disease. PD 90:862-868. Interpretive Summary: Anthracnose is one of the most important fungal diseases in commercial strawberry production. Growers rely on fungicides to control this disease to produce marketable fruit. We looked at the efficacy of pre- and post-infection-period applications of the fungicide pyraclostrobin (Cabrio EG) on the development of anthracnose fruit rot in controlled-climate and field studies in New York and Florida. Our study indicated that for short wetting events (i.e., less than 6 hr), such as those associated with seasonal thunderstorms, growers have the option of waiting until a wetting event occurs before applying a strobilurin fungicide and can expect to achieve control similar to that of a protective spray. Over the course of a season this approach would likely lead to fewer, better timed fungicide applications and may delay the onset of resistance to pyraclostrobin. The results reported in this paper will be useful to growers interested in controlling anthracnose.
Technical Abstract: The effect of pre- and post-infection-period applications of pyraclostrobin (Cabrio EG) on the development of anthracnose fruit rot was characterized in controlled-climate and field studies in New York and Florida. Plants of the day-neutral cultivar Tristar were inoculated with C. acutatum and placed into mist chambers at 14, 22, or 30 C. The plants were removed from the chambers after 3, 6, 12 or 24 h of misting and placed on greenhouse benches to allow disease development. The fungicide pyraclostrobin was applied to the berries at a concentration equivalent to 168 g a.i./ha at 3, 8, 24, and 48 h prior to inoculation and exposure to their wetting period; or 3, 8, 24, and 48 h following inoculation and exposure to their wetting period. Fruit were classified as mature or immature and rated for disease incidence approximately 8 days after inoculation. All pyraclostrobin treatments suppressed disease compared to the corresponding untreated control treatments. The highest incidence of disease occurred on plants exposed to the longest wetness durations (12 and 24 h) or highest temperature treatments (22 and 30 C). As expected, post-infection applications of pyraclostrobin were generally less effective than protective sprays, but provided significant control when applications were made within 6 h after wetting. We further tested the ability of pyraclostrobin to control anthracnose when applied as a protectant or as an after-infection application in inoculated field plots exposed to either a short (8 h) or long (18 or 24 h) wetting period in Florida and in New York. The incidence of anthracnose in the control plots always exceeded that in the treated plots. In plots exposed to 8 h of wetting, disease control comparable to the protective application was achieved with application of pyraclostrobin up to 8 h after an infection. In plots exposed to 18 or 24 h of wetting, excellent control was achieved with applications made shortly after the infection event as long as the conditions for anthracnose were not exceptionally favorable. Our study indicates that for short wetting events, such as those associated with seasonal thunderstorms, growers could wait until after an infection event occurs before applying pyraclostrobin and can achieve control similar to that of a protective application.