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Welcome to SMOR 2007!
Site specific management of resistance (SMOR) is an apple scab fungicide resistance testing service offered by the NYSAES plant pathology biochemistry program at Cornell University. This is the last year the SMOR service will be offered free of charge as part of a grant funded by CSREES-USDA. To participate, please see the description and instructions posted below.
You may also simply click here to view the instructions and click here to download the submission form.
Testing Scab Resistance to Fungicides: Instructions
(Wolfram Koeller and Diana Parker, Plant Pathology, Geneva)
Nine fungicides (Syllit; Topsin M or Methyl-T; Nova, Procure and Rubigan; Flint and Sovran; Vangard and Scala) belonging to four classes of chemistries are labeled for the post-infection control of apple scab. Unfortunately, many of these materials have lost their activity because the scab fungus developed resistance. In response, we have worked on the site-specific management of resistance (SMOR). The SMOR concept is simple: Test the sensitivities of individual orchards and only use the post-infection materials that are still active. Who would do the sensitivity tests to find out where individual orchard stand? We are prepared to provide a limited number of tests in the 2007 season.
We must have 50 apple leaves with scab lesions to do these sensitivity tests. There are two modes of testing, a ‘forward mode’ and a ‘rescue mode’.
In the ‘forward mode’, a scab control failure has not been a problem in previous seasons, but a grower wants to know how much longer the post-infection fungicides will last until resistance sets in. Naturally, leaves with at least one visible scab lesion will not be found easily. In this case, six trees at the opposite corners of a typical orchard block must be left unsprayed until scab lesions develop on cluster leaves. The 50 leaves with scab lesions are then collected and submitted to our test facility. After that, the corner trees are included in all subsequent treatments. Alternatives to such corner trees are unsprayed trees close (no more than 1,000 feet) to the orchard block, or a recently abandoned (no more than two seasons) orchard where scab had been managed with the same fungicide program.
In the ‘rescue mode’, leaf scab develops unexpectedly after post-infection fungicides have been applied. In this case, finding leaves with scab lesions will not be a problem. The leaves submitted for testing must be collected before a ‘rescue’ spray is applied because sprayed scab spores will not germinate and, therefore, cannot be tested.
Collection and Shipment Procedures for apple leaves sent to our test facilities before June 30:
- The 50 leaves with visible scab lesions must be collected from as many trees as possible to reflect the sensitivity of the entire orchard. Try to avoid sheet scab.
- The leaves must be stored in paper bags. Plastic bags must be avoided, because the moisture building up in plastic bags will cause prohibitive problems.
- Once the leaves are collected and stored in an open paper bag, they must be kept at a relatively cool place (lower than 75F). Spores of the scab fungus are very sensitive to heat and will be ‘dead on arrival’, if they are ‘heated up’, for example inside a car or a truck cab on a sunny day.
- The open paper bag with leaves must be shipped to our test facility by ‘overnight mail’. Ground mail takes too long to keep the spores of the scab fungus viable. Prior to ‘overnight shipment’, the leaves can be kept in a regular refrigerator, but never longer than two days.
Leaves should be sent overnight (no weekend delivery) to:
Cornell University’s New York State Agricultural Experiment Station
Attention: Diana Parker
Department of Plant Pathology, Barton Laboratory
630 West North Street
Geneva, NY 14456.
No leaf shipment will be accepted without a completed submission form! Notification to Diana Parker, either by phone (315-787-2400) or by e-mail (dmp2@cornell.edu) prior to the shipment would be much appreciated.