MSU Extension

EPA has granted a Section 18 Specific Exemption for the use of Kasumin 2L (kasugamycin) for the control of the blossom blight phase of fire blight in 2012. This use is for orchards where streptomycin-resistant fire blight bacteria are present. The Section 18 is applicable to Berrien, Cass, Grand Traverse, Ionia, Kent, Montcalm, Newaygo, Oceana, Ottawa, and Van Buren counties.

This Section 18 exemption only applies to counties where we have detected streptomycin-resistant isolates of the fire blight pathogen Erwinia amylovora. We currently have not yet detected any streptomycin resistance in Antrim or Leelanau counties or in eastern Michigan.

Kasumin 2L should be available in each region this year in time for bloom sprays. Make sure you have the Section 18 label in hand when you are applying Kasumin 2L. Do not apply Kasumin through any irrigation system.

The conditions and restrictions of the Section 18 Specific Exemption are as follows:

1. Apply Kasumin only when the pathogen is resistant to streptomycin. We have documented streptomycin resistance in all of the counties listed in the first paragraph above.

2. Kasumin 2L may only be applied when the following condition is met: only when the disease forecasting model or fire blight state expert determine that the weather conditions favor a disease epidemic.

This condition is similar to last year. We have typically utilized the MaryBlyt fire blight prediction model, and have called for Kasumin applications when the Epiphytic Infection Potential (EIP) number from the MaryBlyt model reaches or exceeds 100. This model is available on the Enviro-weather website; use the weather station closest to your orchard location to get local conditions. Make sure to document the MaryBlyt EIP prediction (by printout or screen capture) to include in your spray records. Also, make sure that you document the EIP number when you make the decision to spray – since this number is predicted for the next few days out, the number can change as current conditions and predictions change.

In summary, the use of Kasumin 2L is limited to epidemic conditions; if these conditions are not present this year, other fire blight control materials such as oxytetracycline should be used.

3. A maximum of two sequential applications of Kasumin can be made at a rate of 2 quarts (64 fl. oz.)/acre. Applications are restricted to ground equipment and cannot be made through any type of irrigation system.

4. A maximum of three applications of Kasumin can be used (64 fl. oz. per acre), if authorized. Treatments can be made no later than petal fall.

5. Alternate row applications are not allowed. This is a new requirement of the Section 18 exemption for resistance management.

5. Do not apply Kasumin as the first spray of the season. It should be applied only after the first spray of registered alternatives.

6. Do not use in orchards in which the soil has been fertilized with animal manure. This restriction addresses concerns that kasugamycin resistance could be transferred to E. coli bacteria present in animal manure.

7. Upon expiration of the exemption on May 31, 2012, all unopened and unused product must be returned to the dealer where purchased or to the manufacturer or disposed of in accordance with Resource Conservation and Recovery Act regulations following the expiration of the Section 18 exemption.

Kasumin 2L (kasugamycin), from Arysta, is an alternative antibiotic for fire blight management. Kasumin 2L will work equally on streptomycin-resistant and streptomycin-sensitive strains. The label rate is 2 quarts/acre.

Please note that my lab will also be conducting resistance monitoring in selected orchards this year that use Kasumin. This is to satisfy an EPA directive that we monitor for the occurrence of kasugamycin resistance, and also the potential for resistance to other related antibiotics. We will be taking leaf and soil samples from approximately 10 orchards throughout the state. These monitoring experiments will be conducted after petal fall.

As always, I want to thank Brian Verhougstraete, Pesticide Registration Manager of the Michigan Department of Agriculture and Rural Development for his support of this Section 18 request. Brian submits our request each year and serves as our liaison to EPA.