how to treat influx of Conifer plant pests

Asked September 15, 2019, 4:16 PM EDT

After a wet spring followed by hot summer up at our 8,800 ft Conifer home, our backyard plants are experiencing an onslaught from various predators. The aspens have had an increase in blackening leaves, and new is the leaf infestation of some pest, as displayed in attached picture.
On our healthy Hawthorne tree, we noticed a rusty leaf symptom (cedar Hawthorne rust?) with an opposite side displaying a spiky protrusion. Is this from a fungus?
The most recent and disturbing attack on our yard is from a yellow "ladybug" (maybe Mexican bean beetle?) that has especially overtaken our apple trees but is also on our geraniums and flying up from grass. Their takeover was rapid; since 2 days' time, they are everywhere.

We decided to forego spraying last and this year to encourage butterflies, bees, and beneficial bugs in yard, but the devastation we're seeing now is beyond just using Neem oil to counter. Thinking some of this might be the result of buying from big box store in town and having the larvae in especially the fruit trees already.

Suggestions on effective treatments and an application schedule?

Jefferson County Colorado

1 Response


I apologize for the delay in answering your questions. Based on the pictures you sent I believe your Aspen tree has a form of rust. At this point it is not necessary to treat the rust. It is best to carefully clean up the leaves and discard them, not compost. A fact sheet on Aspen and Poplar Leaf Spots can be accessed here:

The Hawthorn tree appears to have Juniper-Hawthorn rust, a common fungal infection that requires both a Hawthorn tree and a Juniper shrub/tree to complete its life cycle. It is primarily an aesthetic problem that can be controlled with good fall leaf cleanup. If serious infection occurs over several years, treatment options are available, as decribed in the CSU publication

The beetles on your fruit appear to be spotted cucumber beetles. They have been very numerous this year and many gardeners have complained about them on all of the cucurbits, but also on roses and many other flowers and vegetables. At this point it isn’t necessary to treat for them, because they will die with frost. However you need to read up on the various ways to thwart them in the spring. Traps, hand picking, row covers and other methods are discussed in this article. See

If you have further questions or concerns you can bring samples to the Jeffco clinic for evaluation. ($7 charge per sample) The Clinic is located at the Jeffco Fairgrounds,, 303-271-6620.

This growing season has been difficult for many of our plants due to the cool wet spring.