Fire Blight update June 10

Hi fruit growers,

I saw fire blight in two more orchards today plus another grower sent me pictures. I’m worried that most orchards in Rhode Island have fire blight!

I’ve been talking with Debbie Breth from Cornell Cooperative Extension. Debbie has been dealing with fire blight in New York for a couple of decades. I’ll repeat some information I shared last night plus add more information I got from Debbie today:

1. If you have fire blight, plan on cutting out strikes at least 12 inches below tissue showing symptoms. Do this pruning only on dry days and remove prunings from the orchard. Debbie says it’s not necessary to sterilize shears between cuts as long as you are cutting into clean wood (12 inches below diseased tissue). One problem I see with this is when you cut off diseased shoots close to trunks or close to large scaffold branches, you may be cutting branches that are less than 12 inches long. These cuts could transfer the bacteria to your shears – and then you introduce the fire blight bacteria into the next pruning cut. It sounds like a pain in the neck to sterilize shears between cuts, but it may be beneficial on those shorter cuts. Sterilizers to use include alcohol, 10% bleach or 10% Lysol solutions.

2. Don’t spray Strep now and Debbie says Oxidate is not helpful.
3. Spraying Apogee now can be helpful, but it takes 7-10 days for Apogee to start working to protect from future infections.

4. Copper can be sprayed now and not cause fruit finish. This is how Debbie said copper should be applied:

- Some coppers are labeled with a low-dose rate that can be used carefully now. These include Badge, Champ, Magna-Bon, and Cueva.

- You want to apply the copper with no more than 50 gallons of water per acre for small trees and no more than 100 gallons per acre for full-size trees.

- The copper application must be applied only on very low humidity days. I’m not sure we ever get very low humidity days in the summer in Rhode Island.

- Copper can be sprayed weekly until tree growth stops or until you reach the maximum copper per acre listed on the label.

Copper does seem like the best chemical to apply, though it seems very risky. It may make sense for you to apply copper if you don’t have much fruit or you are more worried about your tree health than the finish on your apples.

And please let me know if you think you have fire blight.