There It Was, GONE
Pamela Yelinek, Certified Master Gardener
It seemed it was only a day or so ago you were enjoying the majestic structure of the large agave that stood strong and proud in your yard. The blue green color was striking and the plant stopped passersby in their tracks. You were happy. Today, you notice most of the lower leaves have collapsed lying prostrate on the surrounding rock mulch. The base of the leaves are a pale yellow and have a wrinkled appearance, the plant looks sad and so do you. What happened?Chances are the dreaded Snout Nosed Weevil (Scyphophorus acpunctatus) is the reason for your plants sad state. These half to one inch long, gray/black wingless vectors generally start looking for a place to lay their eggs in the early spring seeking out large agave (and yucca) that have wide leaves and are blue green/blue gray in color. They especially like plants that are about to bloom or are stressed, like those that have been recently transplanted.
At the base of the plant, the female Snout Nosed Weevil will chew a bacteria (Erwinia sp.) laden pencil-sized entry hole to create a tunnel where she’ll lay her eggs. The bacteria start the destructive rotting process and when the eggs hatch, the grub-like larvae continue to burrow and eat their way through to the heart of the plant. The cream-colored legless larvae look similar to the grubs we battle but are much, much larger. It only takes 6 to 12 weeks to go from egg to emerging adult, completing one life cycle and ready to start another.
It’s important to note that, by the time you see the damage, it’s not unusual for plants to be past the point of being saved (even with treatment) and therefore must be removed. Wear gloves and prepare for your senses to be assaulted as the smell is putrid and the sight of the larvae trying to wriggle deeper into the plant is not for the faint of heart!
What can be done to protect/treat the plants you enjoy? The Desert Botanical Garden in Phoenix has an excellent desert gardening resource guide on the Snout Nosed Weevils here. I have used the information to help manage my own yard and encourage you to check it out for yourself to learn about prevention and treatment of these destructive little monsters. Nevada is the Battle Born state so don’t be afraid to fight for your yard!
Post by: Certified Master Gardener Pamela Yelinek