Happy New Year from the Plant and Insect Diagnostic Clinic staff!
This year has started with interesting samples that remind us of the importance of accurate diagnosis as the first step to making management decisions that will best resolve the problem. Correct identification is a fundamental concept and the cornerstone of our integrated pest management extension and outreach activities.
The photos below show leaves of a spike plant submitted to the Clinic. The leaves had yellow discoloration that resembled a disease symptom (caused by an infectious agent or pathogen). But upon closer examination, we observed spidermites (see picture below). The diagnosis of spider mites rather than fungal disease points to very different management recommendations.
Spider mites and pathogens do not have many similarities. Pathogens thrive in high humidity and use water droplets to splash from plant to plant. Mites are mobile and do not rely on water to move. Pathogens, in general, prefer specific kind of plants (i.e., they are usually host plant specific) while spider mites are not picky eaters (generalists). Most importantly, management options that control mites and insects would not control plant pathogens, and vice-versa.
The Plant and Insect Diagnostic Clinic is here to help you. Proper diagnosis of what is wrong with your plant leads to effective and efficient pest management recommendations.
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Horticulture and Home Pest News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on January 15, 2016. The information contained within may not be the most current and accurate depending on when it is accessed.