"Sick" leaves on azalea - Ask Extension
My old azalea bush appear to have a major problem. A similar issue happened years ago but not to this extent. At that time I was told what spray to us...
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"Sick" leaves on azalea #855552
Asked November 19, 2023, 8:59 PM EST
My old azalea bush appear to have a major problem. A similar issue happened years ago but not to this extent. At that time I was told what spray to use, which I did and it helped. I can no longer remember what that was.
I am attaching a picture and would appreciate advise for how to treat it and save it. Thanks.
Washington County Oregon
Expert Response
This looks like azalea lace bug damage. Follow this page (link) from Solve Pest Problems. Confirm that you have the lace bug using, in part, the clear photos given. Control is listed under section 4. For the control steps, note the time of year to use them and note cautions in section 4-E.
Thank you. Yes, these are lace bug damaged leaves, based on the pictures.
Two questions:
1. How effective is the Green Lace Eggs product and how does one apply it and when?
2. What are the commercially available Neonicotinoids?
Thanks, Susan
On Nov 20, 2023, at 5:52 PM, Ask Extension <<personal data hidden>> wrote:
One supplier of green lacewing eggs lists this on the sale page:
" Apply eggs to infested plants at dusk — it protects them from the sun and allows them to acclimate
Rhododendrons, R. canescens and R. periclymenoides cultivars ‘Micrantha,’ ‘Red Slipper,’ ‘Lavender Twist,’ and others show varying insect-feeding resistance."
I'm not able to recommend a brand name insecticide product. Read the labels and choose one that is systemic and lists Azalea lace bug control methods on Azalea plants. It will be a soil drench type of product.
" Apply eggs to infested plants at dusk — it protects them from the sun and allows them to acclimate
- Use within 24 hours of arrival — eggs will hatch quickly
- Predatory lacewing larvae decimate soft-bodied pests immediately upon hatching
- NOTE: To ensure live delivery, please place your order when
temperatures in your region are expected to be between 60-80° F, and
when you can be on hand to receive your shipment. Allow 2-3 weeks for
delivery."
I don't have data on the effectiveness of the lacewings. They become one tool in your general biological pest control plan. This link is to more information about that plan. Predatory insects will help over time, but are not a quick remedy for heavily infested plants.
Section F is about preventing Azalea lace bugs, and is key to getting out of the cycle of purchasing control insects or insecticides. Keep your plants healthy, as stressed plants are less able to deal with the insect damage. Catch the insect damage early, not letting them get this full of pests. Consider replacing your plants with those that are resistant, as the insect is likely to be an on-going problem for your plants. These resistant types are listed in the webpage, and I'll quote it here:
"Plant-Resistant Varieties
The ‘Encore’ series of azalea varieties have shown resistance to insect feeding."Plant-Resistant Varieties
Rhododendrons, R. canescens and R. periclymenoides cultivars ‘Micrantha,’ ‘Red Slipper,’ ‘Lavender Twist,’ and others show varying insect-feeding resistance."
I'm not able to recommend a brand name insecticide product. Read the labels and choose one that is systemic and lists Azalea lace bug control methods on Azalea plants. It will be a soil drench type of product.
Thanks. Apparently nothing about trying to fight these pests is simple or easy to do find…
I do not intend to plant new azaleas, I have way too much trouble with the existing ones.
Have a nice Thanksgiving,
Susan
On Nov 21, 2023, at 1:00 PM, Ask Extension <<personal data hidden>> wrote:
Far from easy. Take care.
Hi,
One more question if you don’t mind. If I decide to use a systemic treatment and find an appropriate product, when would be the best time to apply it? I live in Portland and I assume that there is a most effective time for application based on the lifecycle of the lace bugs. Thanks again,
Susan
On Nov 21, 2023, at 1:00 PM, Ask Extension <<personal data hidden>> wrote:
Susan: This is a very tough insect to manage. There is a systemic insecticide called imidicloprid that is available to home owners in several mixes from different companies. The "Monterey Once a Year Insect Control II" seems to be somewhat available. It is applied as a soil drench and the active ingredient moves from the roots into the plant. Best timing for the lace bug is early April -mid- May. There is some concern about injury to bees visiting the flowers. Data isn't really clear on that score. You will get some (though not as good) control by applying soon after flowering is over. Alternatively, you could apply in April/May timing and hand remove the flowers to reduce the risk. Please read and follow all label instructions on any crop protection products you use.
Sadly, this is an insect has become a serious issue since it got going in the early 1990s. Please feel to call or email me if you have more questions. Chip
Chip Bubl OSU Extension/Columbia County<personal data hidden>
<personal data hidden>
Sadly, this is an insect has become a serious issue since it got going in the early 1990s. Please feel to call or email me if you have more questions. Chip
Chip Bubl OSU Extension/Columbia County<personal data hidden>
<personal data hidden>
Thank you very much for the helpful reply. Happy Holidays!
Susan
On Nov 30, 2023, at 8:44 AM, Ask Extension <<personal data hidden>> wrote:
