Our good friend Josh Rosenstein of Edible Eden schooled the Orchard Stewards on pests and diseases that are common in orchards. We get questions on pests and diseases at least once a week, and a big part of ID-ing something that is attacking your vulnerable trees is being an Observant Orchardist (see October Orchard Stewards blog post!). For example, an apple tree that appears dormant in the winter could actually be fighting off fireblight, which spreads quickly in the spring. Or fly speck could seem like irreparable damage, but it’s just cosmetic damage that’s okay to eat. Josh taught the Stewards how to ID some pesky pests and diseases with the help of the “What’s Wrong with My Fruit Garden?” book that each Steward received.
The lesser peach borer tunnels through wood at the soil line and can girdle a tree in May and October. It’s important to respond to these tough guys in July.
Codling moth starts as caterpillars and worm their way through fruit, creating a sawdust like flesh. They drop to the soil to pupate, so there are multiple ways to respond to this creature. 1) spray the soil and add soil amendments and 2) use a stick to guide the caterpillars and adult moths into a jar of bleach water.
Apple scab reproduces in the winter and attacks your harvest by reducing both the yield and the quality of the fruit. It’s important to remove leaf litter to prevent its reproduction.
Fire blight is spread by creatures and unsafe use of tools. It causes the tree to have burnt-up look and a shepherd’s crook. Trees often quickly die, so you will want to remove that tree to prevent the spread of this nasty disease.
There are many different responses to pests and diseases. The most useful are preventative tactics such as cleaning tools between using them on trees, amending soil, and watering the base of the tree at the drip line. Josh highlighted Integrated Pest Management (IPM) wherein you use the ecosystem to be the best defense for your orchard, such as getting Indian Runner Ducks to eat slugs in your orchard.
Of course, not every orchard is perfect, and you will need to react after ID-ing pests and diseases. Josh found that Surround is a great non-toxic spray for orchards, Bt kills caterpillars, and sometimes a diluted milky spray will do the trick.