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The Strawberry Advisory System in the Mid-Atlantic: a Final Update
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.
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).
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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
Fig.1. The Strawberry Advisory System Webpage
-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).
Farm Treatment Marketable yield (grams) Incidence (%)
Number of sprays BFR AFR The Wye Res & Edu Center SAS 106,079 1 0.4 6 GSD 106,040 0.7 <0.1 9 Trials in Maryland Table 1. Efficacy trials (2017-18 season) conducted on plasticulture strawberries.
Farm Treatment Marketable yield (grams)
Incidence (%) BFR AFR
Number of sprays
The Wye Res & Edu Center SAS 99,609 <0.1 4.5 4 GSD 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. Farm Treatment 2017-18 2018-19 Incidence (%)
Number of sprays Incidence (%)
UME DEMONSTRATION WINES RECEIVE MEDALS FROM AMERICAN WINE SOCIETY
Seven wines from the University of Maryland Extension, Viticulture & Enology Research program were entered in the 2019 National American Wine Society Amateur (noncommercial) Wine Competition that took place on October 29- 31, 2019 at Trade Winds Resort, St. Pete’s Beach, FL. Seven received a medal; here are the results
GOLD NV Russian Collusion (Imported CVS) 1-2% Semi-Dry | WREC
SILVER 2015 Meritage Reserve < 1% Dry | WMREC NV Apple “Ice” Dessert | WMREC
BRONZE NV Chardonnay < 1% Dry | WMREC 2015 Barbera < 1% Dry | WMREC NV Italian CV Blend < 1% Dry | WMREC/WYE/GRV 2015 Chardonnay “Ice” Dessert | WMREC
2016-17 2017-18 Trials in Virginia Table 4. Efficacy trials conducted on plasticulture strawberries during 2016-17 and 2017-18 seasons a .
Farm Field Treatment Incidence (%) Number of sprays Incidence (%) Number of sprays BFR AFR BFR AFR Brookdale Site 1 StAS 21 34 5 5.7 2.3 9 GSD 12 22 11 5.4 1.8 10 Brookdale Site 2 StAS 26 24 5 7.1 8.2 10 GSD 10 24 11 8.1 8.6 11 Cullipher Site 3 StAS 8 10 4 4 3 10 GSD 5 6 10 4.7 1.3 11 Hickory Ridge Site 4 StAS 9 27 5 13 7.3 10 GSD 4 23 10 7 5.3 11
a A, B, or C represents different farms. Strawberry varieties including Chandler, Camarosa, and Ruby June were used for the trials. BFR and AFR stand for Botrytis fruit rot and anthracnose fruit rot, respectively.
Row-cover situation. In addition to the difference in soil condition noted above, the efficacy of StAS may be challenged by difference in cultural practices. In areas outside FL and CA, floating row covers are used to protect berries from frost damage during winter and spring, or to accumulate growing degree-days during fall. The StAS uses on-farm weather stations for model input (i.e. temperature and leaf wetness), which are not capable of monitoring environmental variables under row covers. Whether the deployment of the rowcover during fall or early spring would result in disease infection is unknown.
Available StAS weather stations in the Mid-Atlantic. A total of seven stations were installed in Maryland and Virginia. Among them, two are located in Pungo area in VA and five are located in Fredrick, Montgomery, Charles, Carroll, and Queen Anne's Counties of MD. Based on our observations, disease risk categories (i.e. low, medium and high) between weather stations in western MD were largely consistent over the course of two years, which sometimes are different from Southern MD or the Shore. However, difference in disease risk category did occur occasionally between two StAS locations nearby.
Cost and Maintenance. The cost of having a standard StAS weather station (METOS) manufactured by Pessl instruments is about $3,000. An annual fee of $100 is charged to access weather data such as wind, precipitation, temperature, relative humidity etc., depending on the sensors equipped with the station. The station is solar-panel supported and all data is cloud-based and viewable remotely and constantly. The sensors and solar panel on the station are expected to send back to the manufacturer for maintenance every three to five years. The total annual cost, excluding the purchase of the station, is expected to be $200 to $300.
U NIVERSITYOF MARYLAND VINEYARD LOCATIONS:
WMREC: Western Maryland Research & Education Center, Keedysville, MD WREC: Wye Research & Education Center, Queenstown, MD LESREC: Lower Eastern Shore Research & Education Center, Salisbury MD CMREC: Central Maryland Research & Education Center, Upper Marlboro, MD
OTHER VINEYARD LOCATIONS:
AREC: Alson H. Smith Jr. Agricultural Research & Education Center, Winchester, VA (Virginia Tech) GRV: Golden Run Vineyard, Hans & Jenny Schmidt, Sudlersville, MD
Conclusions. Data from some trials indicated that the StAS may need to be more sensitive especially for highly susceptible cultivars. Recent trials conducted in Iowa also suggested that the StAS might underestimate AFR risk under high disease pressure (Zhang et al. 2019). Overall, we think that the StAS can be a valuable tool to support Mid-Atlantic growers, but fungicides need to be sprayed in time (within 48 hrs. after the warning). Further studies are needed to understand the impact of row-cover on the plant microclimates and disease infection.
Reference:
Bulger, M. A., Ellis, M. A., and Madden, L. V. 1987. Influence of temperature and wetness duration on infection of strawberry flowers by Botrytis cinerea and disease incidence of fruit originating from infected flowers. Phytopathology 77:1225-1230.
Cordova, L. G., Madden, L. V., Amiri, A., Schnabel, G., and Peres, N. A. 2017. Meta-Analysis of a Web-Based Disease Forecast System for Control of Anthracnose and Botrytis Fruit Rots of Strawberry in Southeastern United States. Plant Disease 101:1910-1917.
Wilson, L. L., Madden, L. V., and Ellis, M. A. 1990. Influence of temperature and wetness duration on infection of immature and mature strawberry fruit by Colletotrichum acutatum. Phytopathology 80:111-116.
