Tree Talk

Fire blight bacterium affects fruit trees

Trees, drought stress and pests Part I


With the ongoing exceptional dry conditions persisting, our trees are stressed and stress invites pests.

This month's article will focus on fruit trees. Keep in mind the record-breaking climatic factors: warm winter temperatures, small amounts of snowfall and the lack of precipitation since January.

Our fruit trees, apple and pear, have fire blight, cankers and other damaging diseases.

Fire blight is a highly contagious bacterium, Erwinia amylovora, that affects the new blossoms, shoots, twigs and young branches. The bacteria can survive through winter, hidden in fruit trees, and then oozes in the early spring March and April where insects and bees carry the bacteria to neighboring pome fruit trees.

The fire blight problem is currently widespread throughout Northern New Mexico. You should consult with your local county agent or tree specialist to confirm the tree's (or trees') symptoms.

Here is a fire blight article released June 18 by Dr. Shengrui Yao, associate professor and fruit specialist at the New Mexico State Univerisity's Sustainable Agriculture Sciences Center in Alcalde:

Recently, we noticed some symptoms in apples that are not a good sign.

In early June, we were thinning the apples and noticed some blossom blight (fire blight damage on blossoms), dried spurs with blacked tiny fruit attached, and some had oozes. Last week we pruned out some damaged shoot tips and partial branches.

If you notice similar symptoms, prune out the infected branches. Normally, you should prune out 6-12 inches below the infected parts. If it is in a small shoot, prune it out. It is hard to deal with the individual blossom blight. But if you have several dead spur blossoms in one branch, prune them out.

Please remember: Disinfect your tools between cuts. Otherwise, you help to spread the disease. You can use bleach or rubbing alcohol. You can use two pairs of pruners. Use one and have the other one in the disinfectant after each cut.

For fire blight management, prevention is critical. Once the trees are infected, it is very tough to manage. Normally, fire blight is not a big issue in New Mexico, but somehow it is here this year with limited rain but just the right time for fireblight.

Fruit trees may show early signs of blossom and shoot blight from the fire blight bacterium. You can prune out the infectious part. Keep in mind the trees still need their leaf structure to produce food and maintain their health; do not overprune.

One spraying treatment is with Serenade, a biological treatment; follow the instructions on the bottle.

Here is a YouTube site to watch: "How to Treat & Prevent Fire Blight in Your Organic Orchard,"

Fruit trees give us food, and we should think about building the trees immune systems through good tree care practices.

Water sustains life and trees should be watered weekly and deeply. A good practice is to run soaker hoses or irrigation systems around the drip line (where the branches end) of the tree. The drip line is where most of the absorption roots are located (Mother Nature's design).

Soils are the home of microbial organisms that interact with the root systems of trees. Adding mulch and compost under the tree, 6 to 12 inches away from the trunk and 1 to 3 feet past the trees' drip line, 2 to 4 inches deep, will cool the soils, retain soil moisture and promote a healthy root zone. Soil foods are elements that build and balance the soil profile.

When the leaves drop from your fruit trees treat them with neem oil, fish and seaweed products. These products will help the leaves break down in a beneficial process. If you have a mulching device, physically break up the leaves into smaller pieces. Leaves are one of the best food products that you can give your trees

Any questions, please email the Taos Tree Board -