Ohio

1997 North Central Ohio Tree Fruit IPM Program "Weather-based Predictive Systems for Apple Disease Management"

Principal Investigator:

Ted W. Gastier, Extension Agent, Huron County

Abstract:

Eighteen apple located in the counties of Erie, Huron, Lorain, Ottawa, and Sandusky, enrolled 25 blocks of commercial production. Integrated Pest Management (IPM) methods for monitoring and controlling apple pest insects and mites have allowed these growers increased flexibility in the application of control materials. These growers, however, have lacked adequate the same flexibility in their disease control practices due to the insufficient information about orchard temperatures and duration of leaf wetness events. The environmental factors of temperature and leaf wetness contribute to the development of apple diseases such as scab, fireblight, sooty blotch, and fly speck. Weather monitoring equipment has been installed previously in two orchards but has not been utilized because of calibration factors and lack of grower confidence with the instrumentation.

Implementation:

 Eight sites, chosen as representative of the north central production area, were enrolled in the SkyBit AgWeather Products program during the months of April through September. Four weather products were received each day for the eight sites by e-mail through the AgVAX account of Ted Gastier. Included were:

1.) Hourly Data for temperature, precipitation, and leaf wetness during the previous 24 hour period plus the expected values for the same factors during the present 24 hour period.
2). A 48 Hour and a 7 Day Forecast for temperatures, probability of precipitation, average wind speed, and a spraying key.
3). An IPM Apple Insect Product based on biofixes for Oriental fruit moth, tufted apple bud moth, codling moth, spotted tentiform leafminer adults, and apple maggot.
4). An IPM Apple Disease prediction package for apple scab, fire blight, and sooty blotch.

This information was shared with six apple growers by FAX or e-mail. Monthly precipitation totals, hours of leaf wetness, and mean temperatures were computed with QuattroPro.

Additional daily climatological data for eight Ohio locations was downloaded from (gopher://twister.sbs.ohio-state.edu:70/0/wxascii/climate/climinfo02.K...) where ... represents CAK for Akron-Canton Airport, CVG for Cincinnati, CLE for Cleveland International Airport, CMH for Columbus, DAY for Dayton, MFD for Mansfield, TOL for Toleado, and YNG for Youngstown. This data base also includes historic temperature and rainfall records since 1875. The Cleveland and Toledo locations situated to the east and west, respectfully, of the apple production were used for base comparisons. Data from the other six locations was filed for future Statewide expansion of apple climatological reporting and forecasting. Mean monthly temperatures, normal precipitation, and current precipitation totals were calculated on QuattroPro.

The National Weather Service monthly climate tables for Cincinnati, Cleveland, and Columbus were downloaded from (http://www.NWS.NOAA.GOV/climatex.shtml#dec). This data lists historic records for the 1961-1990 period. Included are monthly mean temperatures; the number of degrees F to be added or subtracted from the mean to reach the threshold of Below or Above normal; and values of Below, Moderate, and Above monthly precipitation amounts.

Temperature readings were recorded manually from two maximum-minimum thermometers located near Milan on a farm central to the north-central production area. A Spectrum Technologies leaf wetness/ temperature sensor was also utilized at this location. Hourly temperatures and periods of leaf wetness were downloaded on a laptop computer with the Spec ware software and printed in chart and graph form. Monthly totals of leaf wetness and mean temperatures were calculated using QuattroPro.

The MARYBLYT software for the predictive forecasting of fireblight was sampled for two orchards with data from the SkyBit Hourly Data Package during April and May. The fire blight predictive portion of the SkyBit AgWeather IPM Apple Disease Product was examined during potential infection periods in May. The disease product is an experimental model under development by Dr. Jim Travis, Penn State University Fruit Pathologist.

1997 Weather Data

Month April May June July August Sept. Oct. Nov.
Mean Temperatures (oF)
Farm 45.0o 52.3o 69.5o 70.2o 67.8o 62.3o 53.1o
SkyBit Central 52.4o 68.7o 70.9o 67.2o 62.4o 52.3o
Spectrum Technologies 61.8o 52.6o 37.4o
Toledo 44.7o 52.8o 68.6o 71.5o 67.1o 62.7o 52.4o 36.5o
SkyBit West 52.2o 68.8o 71.5o 67.3o 62.6o
SkyBit East 52.3o 68.1o 71.0o 67.2o 62.7o
Cleveland 44.0o 52.9o 68.4o 70.6o 67.5o 62.9o 52.8o 39.0o
Precipitation (inches)
Farm 1.55" 8.55" 6.85" 3.95" 6.6" 4.3" 1.45"
SkyBit Central 8.26" 4.00" 1.98" 5.74" 2.67" 1.59"
Toledo 1.55" 6.96" 4.40" 2.62" 3.95" 4.73" 1.24" 2.16"
SkyBit West 8.17" 5.33" 2.30" 4.83" 4.04"
SkyBit East 8.05" 4.25" 1.87" 5.30" 3.12"
Cleveland 2.20" 4.21" 3.34" 1.51" 5.26" 4.25" 1.63" 2.58"
Hours of Leaf Wetness
SkyBit Central 233 187 100 299 219 134
Spectrum Technologies 215 183 256
SkyBit West 218 182 131 264 244
SkyBit East 242 203 99 283 217
KEY: All temperatures in degrees F. Source of temperatures: Farm - maximum, minimum thermometers; Toledo and Cleveland National Weather Service-calculated from daily highs and lows; SkyBit and Spectrum Technologies-24 hour average daily temperatures.
Precipitation at farm from standard rain gauge; National Weather Service measurements at Cleveland and Toledo; and SkyBit from Hourly Weather Product.
Leaf wetness-hourly reports from Spectrum Technology sensor and SkyBit Hourly Weather.

Discussion:

A strong correlation for mean monthly temperatures existed during the 1997 season between all sources of data. This would indicated that temperature readings from the National Weather Service for Toledo and Cleveland might be adequate for determining mean temperatures in our production area. Rainfall events during the growing season, and particularly during summer thunderstorms, tended to lack correlation as would be expected. Examination of the leaf wetness periods indicated that dew was a larger factor than rainfall events. Also dew was usually not occurring until after midnight on a typical summer evening.

One portion of the Forecast Weather Product from SkyBit was considered valuable by growers. The Spraying Key listed expected wind directions and velocities on a 3-hour basis for the next 48 hour period and for each day during the next 7. The Key rated each interval on a scale of 0 to 10 with 0 being least favorable and 10 most favorable to make spray applications. It was assumed that no precipitation was expected during favorable spray periods. Generally a wind speed of 8 mph rated a 6 while a wind speed of 5 rated an 8. Growers found good reliability in using these Spray Key forecasts in planning spray applications. An additional source for wind predictions was found at gopher://twister.sbs.ohio-state.edu:70/0/nmc/FOXE47.KWBC> and will be considered in 1998.

MARYBLYT predictions developed locally generated possible infection periods on May 18, 19, 24, 30, and 31. The SkyBit AgWeather Apple Disease Product indicated possible infection and damage on May 19, 24, 25, and 30. This product, though experimental, might be valuable in future years as a check against local MARYBLYT predictions.

Some minor difficulties were encountered in launching the Spectrum Technologies temperature/leaf wetness sensor which interfered with completing weather information until September from that source. Earlier data was incomplete and not included. Three sensors are now placed and will be ready for monitoring leaf wetness and temperatures during 1998.

Extension Program Implementations:

Growers continue to financially support and participate in a program that make sense economically, allows for the production of high quality fruit, and allows for the judicious use of pesticides based on orchard and weather conditions. As we gain experience in using various weather products, we will build confidence in disease prediction as we have established confidence in our insect and mite monitoring program. A continuing challenge is the timely delivery of information to growers not yet on the Web or with FAX machines.

For further information contact Ted W. Gastier Extension Agent, Ohio State University Extension, Huron County or the Ohio IPM Office.

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