It's a good year for mealybugs and aphids
Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.
When Tom Dudek finished reading the scouting reports from greenhouses this week he sighed, then called me with the news: lots of mealybugs and aphids. The mealybugs probably came on rooted cuttings and other plant material brought in months ago. We are seeing them now because they have had time to complete one or two generations, which can increase the infestation 100-fold. Mealybugs have been found mostly on Ipomea, but they are capable of feeding on many other plants as well. The aphid problems have been reported to be on Ipomea, peppers, Springerii, spikes, Digitalis, Shasta daisy, gerber daisies, dusty miller and licorice plant. Because mealybugs and aphids are closely related, the same insecticide products will be effective for both. The only difference is that mealybugs are notoriously difficult to get rid of, so growers may want to pitch the most heavily infested plants and spray all the remaining plants in the area. The best products to use for mealybugs and aphids are systemic insecticides absorbed by the roots. This includes:
All of the above products should be applied as a soil drench, or as a spray directed to the surface of the soil, followed with enough overhead watering to wash them into the soil. Stop watering before water begins dripping out the bottom of the pots. Avoid over-watering for the next two days to all plenty of time for the insecticides to be absorbed. Marathon, Discus and Celero may take a week or more before you see dead mealybugs and aphids, but they also last the longest (six weeks or longer). Safari and Flagship work somewhat faster, and you may dead insects within a few days to a week. They should continue working for at least 2 to 4 weeks. Aria will work very quickly, with dead insects being seen in one to three days. Most of the Aria will be gone from the plant within a week.
The products listed above can also be used as a foliar spray. Foliar sprays work because of contact activity. Most of the benefit from the foliar sprays is in the first week after spraying. For heavy infestations a soil drench and a foliar spray can be used at the same time or close together to help bring the aphids or mealybugs under control quickly. In addition to the products listed above, the products below can also be used as a foliar spray:
- Enstar II
Dr. Smitley's work is funded in part by MSU's AgBioResearch.