Solving plant problems

Monday, June 17, 2024

By JENNA NEES, Purdue Extension Educator

Jenna Nees

Too much rain, extended cold temperatures in late spring/summer, a sneaky insect pest, a plant disease. All of these can cause individuals frustrations when trying to grow plants. This article provides a current overview of plant issues challenging farmers, gardeners and homeowners.

The first step in solving a plant problem is looking for evidence. Taking a representative sample in a timely manner is crucial. The next step is to determine if the problem is caused by a living organism (biotic) or a nonliving causal factor (abiotic). For example, purple corn is showing up in the area and sometimes makes growers think a plant problem is being caused by a chemical. What was happening is due to cool, wet weather and the lack of uptake of phosphorus (P). This is not caused by a low soil test level, but because environmental conditions have limited the corn plants’ uptake of P.

Other abiotic factors we are seeing in the area include soil compaction, poor rooting due to wet planting conditions and winter injury of landscape plants (boxwoods took a beating with the cold snaps of December 2022 and December 2023). Knockout roses look ragged because of the cold winter injury. Herbicide drift is another potential abiotic causal factor that requires careful investigation by the Office of the Indiana State Chemist.

Once we rule out abiotic factors, then we evaluate possible biotic factors. The big player in biotic factors are fungal diseases like fusarium, blight and rust. About 85 percent of biotic factors are caused by fungus. Insect damage is always a challenge, because so much of their damage is caused when we are not present. Insects either chew on a plant or suck the sap. Cabbage riddled with chewing holes is often caused by the cabbage looper, the larval stage of the white moth hovering around your brassicas (broccoli, Brussels sprouts, cabbage, cauliflower, kale and turnips, for example).

After we identify the cause, we can take appropriate measures to treat the issue. Sometimes we have no real treatment to recommend, like the dead boxwood. Other instances may warrant a pest control treatment and suggested label recommendations. We don’t recommend home remedies that are not research-based. For example, moles are not repelled by chewing gum or mothballs, and there is no research to support this or many other common mole control methods.

The summer is young and plant problems will keep coming until frost. Contact the Purdue Extension-Putnam County office at 653-8411 or e-mail smith535@purdue.edu with photos and information about the different plant problems you are dealing with. If the problem is more challenging, we can arrange a site visit. Challenging issues may require submitting a sample to the Purdue Plant and Pest Diagnostic Lab (PPDL) for $11. Some inquiries will not justify $11, so Purdue Extension will try their best to identify the issue and provide a control recommendation without the expense.

Visit www.extension.purdue.edu/putnam or contact the local Purdue Extension office at 653-8411 for more information regarding this week’s column topic or to RSVP for upcoming events. It is always best to call first to ensure items are ready when you arrive and to RSVP for programs.

Upcoming Events

June 19 – Extension office closed for Juneteenth county holiday

June 19 – Electric 4-H workshop, Extension office, 3-6 p.m.

June 20 – “Field and Followers: How to Track Impact on Social Media” webinar, 12 p.m., register at https://tinyurl.com/2p5jzy97

June 25 – “Harvesting Her Voice” workshop, 6 p.m., Cloverdale, $5, register at https://tinyurl.com/4mnwcfy9