Fire Blight Treatment

Old Monkey

Mar 9, 2005
A customer the other day asked my opinion of using antibiotics on apple trees to prevent the spread of fire blight. I admitted to her that I had only ever treated fire blight by mechanical means, removing branches beyond the point of infection and cleaning disinfecting my tools with a bleach solution or lysol. Do any of you guys know about treating trees for fireblight? I know that there isn't a cure just preventatives. I searched AS and found a two page thread that questioned whether cleaning you snips between cuts it necessary. I guess some guy named Shigo said that it couldn't hurt to sterilize your tools but that no conclusive studies had been done on spreading disease with tools.

What are your thoughts?
When I had a commercial apple orchard I treated it with antibiotics to limit the spread of fire blight. During the bloom period is when most blight is transmitted so we had a set of criteria that triggered a spray. During bloom, somewhat warm weather (I think it was 70 degrees or warmer) and a chance of rain and or humid weather. You put the spray on in anticipation of these conditions. Some apple varieties were much more susceptable than others. The Fuji variety that I had was very susceptable and the Granny Smith variety wasn't. One of the big problems was people with their damm back yard trees that didn't treat them made for a lot more blight spores floating around. Any wound is also a potential blight infection site. We did some summer pruning in July or so and we would remove any blight "flags" at that time.
I've been out of the biz for 8 years but as far as I know Shigo was right regarding the disinfection of tools. Each crewmember would have a little spray bottle with a bleach solution in it to spray his pruning shears with. IMO apples make a pretty poor yard tree because of all the spraying that must be done to have a worm free crop plus the blight spray, thinning, dormant spray and fungicide bloom sprays.
There are stuidies showing some effectiveness of Streptomycin spray during the bloom period. And studies showing efectiveness of a Bordeaux mixture applied during the same time. Mechanical removal is a proven method. The disinfecton of pruning tools is still recommended but there is NO conclusive evidence of transmission of fireblight via pruning tools and mounting evidence that almost all transmission is done during pollination.
We were told that any copper on the apples after the start of bloom could cause some little russett looking spots on the apples rendering them unmarketable. So, right or wrong we used Streptomycin. Expensive spray to say the least.