Additions to the IPM Toolbox -- The Strobilurin Fungicides

This year there is a new group of fungicides  in the IPM toolbox  -- the strobilurins ('stroby') which include the fungicides Flint and Sovran. Their chemistry has its origins in a natural compound produced by the mushroom, Strobilurus tenacellus.   Flint is manufactured by Novartis;  its generic name is trifloxystrobin.  Sovran is manufactured by BASF and has the generic name kresoxim-methyl.   These materials are considered to have low toxicity to birds, earthworms, beneficial insects and mites, and mammals. 

The following is a synopsis of information presented at the Vermont Tree Fruit Growers Association Annual Meeting on February 10, 2000:

Note the following precautions:

Also note that both labels have information on Resistance Management.  Since these fungicides have very specific modes of action,  it appears that it is not a question of whether resistance will develop but when it will appear.  Therefore, it is important that they be used judiciously  from the beginning in order to delay resistance.


Where do these new fungicides 'fit' in your disease management program?

As you might expect, there is no one answer.   When choosing a fungicide, there are at least four factors to consider:  efficacy,  resistance management, non-target effects on beneficial organisms (e.g., insect or mite predators), and cost.   In deciding where these new  fungicides fit into your disease management program an important question to ask yourself is: "How best can I optimize the benefits these new fungicides offer at a cost that I can afford?" 

It would appear that one optimal time for use would be around Petal Fall  through 2
weeks afterwards where you would get benefits from their  efficacy against apple
Scab (both protec-tive and post-symptom, anti-sporulant activity ... in situations
where some primary scab has developed), it is a key time for powdery mildew ma
agement, and,potentially, they would  impact sooty blotch & fly speck development
Another option is to take advantage of their excellent  "after-infection" activity
against apple scab and use them when you have missed an infection period sim
larly to how the SI fungicides have been used by some growers.  Again, judicious
use is important for resistance managment.

Good success with these new tools !

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