katesflowers said:I slit the stem on two plants removed from the garden with wilting problem. One plant had a healthy, white inner core and the other had a hollow dry, brown inner core, no borer was detected.
Hi Kathy,
The cause for the death of the plant whose stem had a healthy, white inner core would remain a mystery. However,, on long stems like that, it is easy to miss localized borer damage. I have had zinnias that had a small hole in the stem near the soil surface and a relatively short hollowed out segment from the soil surface, or slightly below, up to maybe an inch or a little more above the soil. Just that localized amount of damage was enough to kill the zinnia plant.
Keep your eyes open for more plants that show signs of distress, and look for those tell-tale small holes in their stalks or stems. Those would be entry or exit holes made by stalk borers. If stalk borers are involved, hopefully you will eventually catch one "in the act".
ZM
