May 24, 2002

Brown Recluse Spider in Iowa

Recent news coverage about the brown recluse spider in Iowa has sensationalized our situation and lead to unnecessary concern. We hope the following points help clarify the situation. Please also refer to ISU Extension pamphlet Pm-1721, "Potentially Dangerous Spiders."

Fire Blight

Fire blight is a common disease of plants in the rose family caused by the bacterium Erwinia amylovora. Apple, crabapple, pear, fire thorn, hawthorn, and quince are some of the most susceptible species. Symptoms first appear in the spring as new shoots turn black and bend downward forming a "shepherd's crook". Leaves droop and turn a dark color. Individual branches may look like they were scorched by fire.

Grape Tomatoes in the Home Garden

A recent addition to the tomato world is the "grape" tomato. The shape, size, and sweet taste of grape tomatoes is similar to the fruit on grapevines. Oblong-shaped fruits weigh between 1/3 to 3/4 of an ounce and are produced in clusters of up to 30 or 40. The culture of grape tomatoes is similar to other tomatoes. Planting, fertilizing, and other cultural information can be found in extension publication PM 608, Tomatoes . Grape tomatoes are reported to be almost crack-free, increasing the yield of edible tomatoes.

Identification of Woody and Herbaceous Plants

To facilitate plant identification, please follow the guidelines listed below when sending tree, shrub and herbaceous plant specimens to the Horticulture Department.

The Meaning and Importance of Soil pH

Garden soils are often described as acidic (sour) or alkaline (sweet). Unfortunately, the meanings of these terms and their relationship to plant growth are not clearly understood by some gardeners. The relative acidity or alkalinity of soil is indicated by its pH. The pH scale runs from 0 to 14. Any pH reading below 7 is acidic and any pH above 7 is alkaline. A pH of 7 indicates a neutral soil. The pH is important because it influences the availability of essential nutrients.