Issue: June 1, 1996


Maples don't like New Mexico

Question: We live in Albuquerque and planted a red maple three years ago. It's now about eight inches in circumference and 12 feet tall. It leafed out fine this year (it's been on a drip system and got water during our dry winter), but now the leaves have brown margins all around them. Same thing happened last year. I suspect those big fat grubs that are common in the earth could be damaging the roots. Help!

Answer: The good news is that the problem is probably not due to grubs. The bad news, really bad, is that most maples do not like New Mexico's dry air, our dry soil, and they especially do not like the high pH and calcium content of our soils. The symptoms you described are most likely due to desiccation caused by our hot dry summer winds.

Smaller maples may be planted in locations which provide shielding from our drying winds, but larger trees are at the mercy of whatever New Mexico wants to throw at them. Most maples are just not a good choice for New Mexico landscapes, except in very protected locations with many surrounding trees and perhaps in the most northern parts of the state in the mountains. The native big-tooth maple is better adapted than the other maples and will do well in some parts of the state. It has shown itself to be adapted to Albuquerque and mountain locations.

Another common symptom that maples exhibit in New Mexico is iron chlorosis. This is the yellowing of leaves while the veins remain green. Iron chlorosis is due to the fact that maples and many other plants not native to high pH soils cannot extract iron the soil. In severe cases, following the development of interveinal yellowing, the leaf edges turn brown and the leaves fall early. In time, twig and stem dieback may occur. While iron applications and temporary acidification of the soil in the root zone of affected plants may provide some relief from the problem, in the case of trees and large shrubs, the battle is continuous. The problem is avoided by using plants better adapted to our soils.


Squash bugs

Question: All of a sudden I have found gray bugs with black legs on my squash plants. They weren't there yesterday, now they are everywhere. What are they and are they harmful?

Answer: You have the infamous squash bug. They do seem to suddenly appear out of thin air. They are very debilitating to squash plants and may carry plant diseases which compound their damaging effects.

They are difficult to control. Mechanical control by physically removing and killing them is one method. Also, look for their masses of shiny brown eggs on the underside of the lower leaves. Smash the eggs when you find them. Sabadilla dust and carbaryl insecticides are effective when the squash bugs are very young. As the bugs get older, the insecticides become much less effective and mechanical control becomes the preferred method. If you use insecticides, follow the directions on the label carefully to maximize their effectiveness and safety.

Some people delay planting squash until July to avoid the squash bug. Dr. Charles Ward, Extension Entomologist, warns that delayed planting will not always be successful. In my garden, he was correct this year. I planted late and still suffered a squash bug attack. Now every morning I must go on bug patrol, rubbing them out (literally) when I find them.

Good luck!