Insects
Eriophyid mites on Burning Bush?

The samples that have trickled in from Kentucky nurseries lead UK entomologist Lee Townsend to believe that the symptoms shown below are caused by an eriophyid mite. Because the actual insect hasn't been recovered the identification is tentative. (The Kentucky Nursery Update strives to bring only confirmed identifications, but because this problem is on a plant of significant economic importance, it is being featured.) The symptoms are consistent with the damaged caused by pear blister mite, another eriophyid mite (See Kentucky Nursery Update #27). While the initial observation is that the damage is merely cosmetic, that may mean dollars to many nursery growers and their customers.

Eriophyid Mites
Eriophyid mites cause unsightly galls with little consequence to plant health. Eriophyid mites are specific to a host plant, attacking just one type of plant. The mites are extremely small (a hand lens or microscope is necessary to see them). They overwinter as specialized winter females on the host plant in cracks and crevices in the bark and bud scales. Adults emerge in the spring and reproduce. The adults live for approximately one month, with multiple generations per year. The mites inject a chemical as they feed which causes distorted growth of plant tissue. Dormant oil or a miticide can be applied in early spring. For a review of miticides available for use in nurseries, please see Kentucky Nursery Update #33.

Small brownish-grey bumps on upper leaf surface.

Left: Damage on Euonymus alatus 'Compactus' in Kentucky

Right: Damage on Euonymus phellamanus in Oregon

At the 2005 Southern Nursery Association research conference and trade show in Atlanta, researchers from Auburn and Oregon reported on preemergence weed control on container crops. They tested a topdress of pine bark nuggets (0.79-2.36 inch nuggets) at 0, 1.5" or 3" deep. They seeded the pots with bittercress seeds both before and after applying the mulch. In addition, they applied Broadstar 0.25G at 150 lb product/A to half of the treatments, after all mulch and seeds were applied. They found that 180 days after treatment the pine bark nuggets applied 3 inches deep before seeding provided excellent control. At 180 DAT bittercress was growing vigorously in the control containers (no mulch-no herbicide). These containers averaged 100% coverage of container surface. In comparison the no herbicide, 1.5 inches of mulch treatment with seeding after mulching, averaged 44% coverage of container surface by bittercress. Both treatments resulted in greater bittercress growth than all other treatments. As you can see, the Southern Nursery Association has gone national and, in fact, international, with researchers from Mexico and Italy reporting on their latest nursery research. In addition to research reports, SNA is a great way to network with growers from all over the Southeast, meet new customers, and maintain good relations with existing customers. Proceedings of the SNA research conference are available online. The site features a keyword search.

Don't forget that weeds between containers are a source of weed seeds. Weeds like eclipta can become established in the drainage holes and out-compete the plant for water and nutrients.  Using a ground cloth barrier will help suppress weeds under the covered area, however, debris from plants and spilled bark creates an environment where weeds can establish on the surface of the ground cloth.  Keeping on top of weed control all season long will help to reduce the number of weed seed for next year and will make weed control in overwintering houses a little easier.

From the West Coast:
Approximately 20 horticulture and landscape architecture students and UK faculty and staff toured nurseries and botanical gardens throughout Northern California, Oregon, Washington, British Columbia, and Alaska in August. The group spent a week visiting nurseries in the Portland area, touring approximately four nurseries per day, including some of the most innovative and successful nurseries in the US. What a great training program for your future employees! Arrangements are made by Dr. Robert McNiel, who has recently retired from his Extension responsibilities but continues to teach, conduct research and advise the Horticulture Club. To find out how you can provide financial support to this program, please contact Dr. Dewayne Ingram 859-257-1758 and ask about the Robert E. McNiel Horticulture Enrichment Fund. Double, triple, or quadruple the impact of your donation by helping the fund retain a $50,000 state contribution! A big thank you to those who have already given.