No. 10/June 28, 2013

Last Weekly Issue
This is the last weekly issue of the Home, Yard, and Garden Pest Newsletter for this year. During the summer, there are fewer pests and management timing is less critical than in the spring. Issues will be published every other week during July, August, and September. We will publish a final issue in mid-October that will include an index to articles published during the year.

We have had several reports of columbine and other leafminers around the state. They appear to be more numerous this year, probably due to the heavy and frequent rains this spring. Most full grown leafminer larvae burrow out of the leaf and drop to the soil to pupate. Dropping onto moist soil increases their survival, resulting in the next generation being more numerous. I don’t remember seeing entire leaves covered with columbine leafminer mines previously, as in the accompanying photo.

Japanese Beetle
Thanks to a variety of readers that responded to the article last week on Japanese beetle. I can now report that they have been present in southern and central Illinois since the third week of June and were seen in LaSalle and Will Counties on June 24. With the warm temperatures of the past week, they should have emerged in the rest of northern Illinois by now.

Bagworms have hatched throughout the state and appear to be a little early than normal. Treatment is recommended in southern and central Illinois at this time as they have completed their ballooning and are settling down to feed in earnest. They will still be ballooning in northern Illinois, so treatment should be effective after the fourth of July.

What Does Plant Disease Sanitation Really Mean?
A plant pathologist’s goal is to properly identify and manage plant disease to reduce the economic and aesthetic damage to plants. Unfortunately, many still think that our goal is to control plant disease by spraying fungicides. We focus on an integrated disease management approach, which includes exclusion, eradication, protection, and resistance.

Recommendations for sending suspected oak wilt samples to the U of I Plant Clinic
Summer has arrived. Along with the new season, comes days with extreme temperatures. High temperatures have the potential to kill plant pathogens and thwart diagnostic efforts before the samples arrive at the Plant Clinic. The pathogen responsible for oak wilt is a good example. This fungal pathogen is intolerant of temperatures above 90°F. It is also thought to be sensitive to drying and other competing fungi. Exposure to these conditions during shipping may result in inconclusive text results. Properly packaging and shipping samples will greatly help reduce the potential for an inconclusive diagnosis.

Asiatic Dayflower The Little Beauty that Caused So Much Confliction
The jury is out on Asiatic dayflower. Half of them are out enjoying how their gardens have been graced with this plant’s pretty blue flowers. The other half is and likely has been for quite some time waging war on this invasive weed. How can we be so divided when it comes to this plant?

Modified Growing Degree Days (Base 50° F, March 1 through June 27)
Insect development is temperature dependent. We can use degree days to help predict insect emergence and activity. Home, Yard, and Garden readers can use the links below with the degree day accumulations above to determine what insect pests could be active in their area.