June 13, 2009
Posted: June 13, 2009
Fireblight
Fireblight is a bacterial disease that affects apple, crabapple, mountain ash and pear trees.
Cherry, peach and other related species are NOT affected by fireblight, a sometime serious disease.
Most often, springtime weather that is warm and rainy encourages fireblight. Bees and other pollinators may introduce the disease to blooming trees during pollination. As a result, symptoms often begin in the blossom, which develop brown, mushy-looking petals.
More commonly, trees with fireblight develop curling, bending and blackening shoots, called shepherd’s crooking. Leaves turn yellow, then brown and finally black but remain on the branch.
Manage fireblight with a combination of resistant varieties and pruning. Removing diseased parts of the tree is always recommended. Pruning can be done anytime of the year, but it is best during March when trees and diseases are still dormant. Prune fireblighted trees when symptoms develop in the spring and early summer. If pruning during the growing season, when the disease is active, it is extremely important to sanitize pruning tools BETWEEN EACH AND EVERY CUT.
Chemical control of fireblight is an option, but it’s not always effective. Copper sulfate can be used before leaves form in early spring. Another chemical, streptomycin sulfate, can be used when blossoms begin to open. Follow label directions carefully.
Tobacco Budworm
Tobacco budworm is a serious pest of geraniums, petunias and other Garden flowers in Colorado. In several other areas of the country, people no longer grow geraniums or petunia because of damage caused by geranium budworm.
Budworm caterpillars attack buds of developing flowers. Damaged buds don’t open, and lack of flowering usually is the first injury observed. Flowers that do emerge appear ragged and have a chewed appearance. As insects feeds through the summer, the damage increases and becomes even more noticeable.
The larval stage of the insect causes the damage. Larvae are marked with several stripes. The overall color of larvae varies from red to green or brown. Caterpillars become full grown in about one month and then drop to the ground to pupate. There are two generations per year.
The most effective way to manage tobacco budworm is to monitor plants for damage. Check buds and flowers for small holes, and hand-pick damaged flowers from small plantings. The best time to check for budworm is during dusk. That’s when larvae are most active.
Chemicals available to homeowners haven’t proven their effectiveness against tobacco budworm larvae. Certain varieties such as ivy geraniums are damaged less frequently than standard geranium types. Removing soil and repotting plants can be an effective management tool if plants are kept between seasons.
Source: Planttalk Colorado