Issue: October 20th, 1997

Yellow areas on tree leaves

The leaves on several of my trees have irregular yellow areas and are falling from the trees. Do my trees have a disease and what can I do?

I discussed this with the Extension Agent in Lea County. From his description and information regarding the insects which have been common in your area this year, we believe that you are seeing damage from an insect. Leafhoppers and plant bugs may inject a phytotoxin with their saliva when they feed on a leaf. This phytotoxin is a chemical which damages the leaf cells in the area around the feeding site. The irregular pattern is due to the toxin spreading until it reached the veins which bound that area of the leaf.

According to Wallace Cox, Lea County Extension Agent, plant bugs have been common in the latter part of the summer and are the most likely candidates as the cause of the problem. While there are insecticides for these insects, the problem will be eliminated soon as the leaves fall from the trees. Treatment with insecticides may still be advisable to avoid problems next year. Look for a product which is made to use on the types of plants you have found damaged and to control the insect causing the problem. If it is possible to collect a sample of the insects you see on the tree, your county agent can help you confirm which insect must be controlled.

Too late to plant bulbs?

Is it too late to plant bulbs?

No, now is a good time to plant most of the spring flowering bulbs and some of the summer flowering bulbs. Here in New Mexico, we can plant them until about Christmas, or until the soil freezes and becomes too difficult to dig.

Be sure to incorporate some phosphorus into the soil below the bulbs and to plant the bulbs at the proper depth for what you are planting. While it is important not to over-water the bulbs after planting, it is also necessary to provide some moisture in the soil through the winter. Soon after planting, roots will begin to grow. Some of the spring flowering bulbs produce their leaves in the fall and carry them through the winter. They can provide some green in the winter garden.

After the first of the year, it becomes very important that moisture be available to the bulbs. Short flower scapes and short-lived flowers are the result of insufficient irrigation.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu, or at the Desert Blooms Facebook.

Please copy your County Extension Agent and indicate your county of residence when you submit your question!