February 20, 2008

Plant and Insect Diagnostic Clinic Update - February 20, 2008


We receive samples of plants from greenhouses this time of year. Most often, problems on greenhouse plants (and indoor houseplants) are caused by factors other than infectious diseases, such as improper pH, too much or too little fertilizer, imbalanced nutrients, or temperature problems. This oxalis (shamrock) plant has crinkled, mottled leaves due to cold growing temperatures.

Larger yellow ants


Larger yellow ant workers are about a quarter inch in length and very yellow in color. When disturbed, larger yellow ants release a compound smells to humans very much like citronella or lemon. Larger yellow ants eat the honeydew of aphids and mealybugs feeding on the roots of plants. Honeydew is essentially the excrement of these pests that contains plant sugars and other nutrients. Since larger yellow ants feed primarily below ground and there colonies are below ground, we seldom see them outside in our gardens.

Forcing Branches of Spring-Flowering Trees and Shrubs


The winter of 2007-2008 has been difficult (both mentally and physically) for many Iowans. The state has experienced ice storms, heavy snows, and brutal wind chill temperatures. And winter isn't over yet! Gardeners can brighten up the last few weeks of winter by forcing branches of flowering trees and shrubs indoors. Forsythias, pussywillows, serviceberries, crabapples, magnolias, redbuds, and many fruit trees can be coaxed into early bloom indoors, helping revive the spirits of winter-weary Iowans.