Ponderosa Half Dead? Is there hope?

Asked October 2, 2019, 3:11 PM EDT


We have a beautiful ponderosa in our backyard that has started to struggle in the past year. Last spring/summer (2018) there were thousands of tiny black ants crawling up and down it. Then by fall half of the tree looked dead...all needles on west side turned brown. The local nursery recommend a systemic insect drench for the ants, although they suspected the ants to be a secondary issue not the primary problem. By this spring the ants are gone but the brown needles seem to keep spreading, up and around the tree. The only change in the past several years could be the amount of water the roots are getting. We live in the high desert of NM and at our elevation, ponderosa's are scarce. Our annual rainfall has diminished and our neighbors also poured a long slab of concrete along the fence line which used to drain right to the tree. So, some questions I hope you can answer. 1. Is there hope still for this tree? 2. Should we be cutting/removing the brown, dead branches? 3. Should we apply more systemic treatment? 4. Should be watering the tree (something we have never done)...and if so, how often? Appreciate any expert advice we could get for our great tree.

McKinley County New Mexico

1 Response

It's difficult to say whether this tree will survive. There is quite a lot of damage. The presence of ants usually indicates an abundance of aphids. Aphids are a sucking type of insect that are able to penetrate into the tree to obtain their food. They produce a nectar which is desirable to ants. The ants in turn tend to cultivate the aphids to keep them feeding on the plant to produce the nectar. Try to continue the use of the systemic pesticide. One that seems to work well is the Bayer Tree and Shrub Protect and Feed. I have used this on some Austrian pines that are in my yard that worked out well. Also start watering the tree, even in the winter time if the ground isn't frozen, Trees can dry out in the winter if temperatures are warmer than usual and if it becomes windy. Also try an extended watering period that can really soak the soil about every two three weeks. The amount of water will depend on the soil texture. If it's sandy, then you will not have to add as much water during the watering periods, but you may need to water more frequently. If the soil is clay, then water for longer periods but less frequently. Avoid over watering. If it becomes colder, then reduce the watering frequency. Continue watering into the summer. Factor in the need to water based on air temperature and prevailing winds. Again, do not over water. You can remove the dead branches if it's possible. There are quite a lot of dead branches higher in the tree which may be difficult to remove. Dead branches tend to be good entry points for more insect activity.