The Strawberry Advisory System in the Mid-Atlantic: a Final Update Mengjun Hu, Ph.D., Department of Plant Science and Landscape Architecture, University of Maryland, College Park, MD
As many of you are aware, the Strawberry Advisory System (StAS), a disease forecasting system, is now available to support regional strawberry production. This project, funded through USDA-NIFA and Horticultural Society of Maryland, was initiated by former UMD small fruit pathologist Dr. Cassandra Swett. The StAS, originated at University of Florida (led by Dr. Natalia Peres), utilizes site-specific weather stations to monitor leaf wetness and temperature to predict infection risks for Botrytis fruit rot (BFR) and anthracnose fruit rot (AFR) in real-time based on the disease models developed previously (Bulger et al. 1987; Wilson et al. 1990). The beauty of StAS is that users can virtualize the real-time infection risk at AgroClimate (http://cloud.agroclimate.org/tools/sas/dashboard/disease) or through the smartphone app SAS (Fig. 1). Free subscriptions of email and/or textmessage are also available to get timely alerts for fungicide applications when there is medium or high risk of AFR or BFR infection. Fig.1. The Strawberry Advisory System Webpage With the capability of predicting disease infection, it can improve timing of fungicide applications to avoid unnecessary sprays. According to 39 field trials conducted mainly in Florida from 2009 to 2014, no significant differences were found in BFR/AFR incidences, yield and number of marketable fruit between the StAS and calendar-based treatments in each trial. However, the number of fungicide applications was reduced by 50% on average when using the StAS compared with the calendar-based spray schedule (Cordova et al. 2017). Trial data. From 2017 to 2019, field trials have been conducted in Maryland and Virginia on both matted-row and plasticulture strawberries to validate the efficacy of the StAS in the Mid-Atlantic region. Overall, the performance of the StAS is acceptable. Marketable berries, disease incidence in the trials were largely comparable between the StAS and calendar
-based spray schedule (Tables 1-3), despite that the StAS seemed to be associated with slightly higher incidence of AFR or BFR. However, unacceptable results were also noted in the trials conducted in VA during 2016-2017 season (Table 4), presumably due to fungicides not sprayed in time. Unlike FL, many fields in the Mid-Atlantic that have received more than an inch of rain are often too soft and wet to spray within 48 hours, a timeframe required by the StAS. In order to address this issue in the following season, fungicide sprays were made just before a likely rain event that may result in more than 1-inch of rain, if the field had not been treated in the last 5 days. As a result, no significant difference in BFR and AFR incidences was observed between the StAS and calendarbased sprays in the 2017-18 season (Table 4).
Trials in Maryland Table 1. Efficacy trials (2017-18 season) conducted on plasticulture strawberries. Incidence (%) Farm
Treatment
Marketable yield (grams)
Number of sprays BFR
AFR
SAS
106,079
1
0.4
6
GSD
106,040
0.7
<0.1
9
The Wye Res & Edu Center
Table 2. Efficacy trials (2018-19 season) conducted on plasticulture strawberries. Farm
The Wye Res & Edu Center
Treatment
Marketable yield (grams)
SAS GSD
Incidence (%)
Number of sprays
BFR
AFR
99,609
<0.1
4.5
4
97,753
<0.2
1.0
6
Strawberry varieties including Rutgers Scarlet, Earliglow, Flavorfest, Allstar, and Chandler were used for the trials. BFR and AFR stand for Botrytis fruit rot and anthracnose fruit rot, respectively. GSD stands for grower standard.
Table 3. Efficacy trials conducted on matted-row strawberries during 2017-18 and 2018-2019 seasons. 2017-18 2018-19 Farm Treatment Incidence (%) Incidence (%) Number of sprays Number of sprays BFR AFR BFR AFR StAS 6 0 4 0 0 5 Larriland GSD 0.1 0 7 0 0 7 Strawberry variety Flavorfest and Galletta was used for 2017-18 and 2018-19 respectively. No yield difference was found between the two treatments for the sampled plants. continued on page 8
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