It finally feels like summer in New Jersey. Rain, humidity, and warmer temperatures, especially at night, mean that warm-season weeds are growing quickly. Of particular concern are summer annuals like crabgrass, goosegrass, and spurges. Yellow nutsedge and false-green kyllinga are warm-season perennials are also enjoying the weather. These weeds are now growing more quickly than […]
Landscape, Ornamentals, Nursery, and Turf Edition
Seasonal updates on ornamental, nursery, and turf pests.
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Landscape Pest Notes for Late June 2023
Azalea Lace Bugs (802-1029 GDD = 3rd generation): The third generation of this pest will be in full swing for much of NJ by the end of the month. Look for the presence of nymphs (spiny, black), adults (larger, lacy wings), fecal spots (brown, shiny spots) on the underside of leaves, and stippling (feeding damage from nymphs and adults) on the leaves. Remember that the yellow stippling damage persists on the leaves until they are dropped. Look for the presence of actively feeding lace bug nymphs or adults before treating plants.
![Azalea lace bug feeding symptoms.](https://plant-pest-advisory.rutgers.edu/wp-content/uploads/2023/06/aaaa-Lace-Bug-Azalea-1.jpg)
Azalea lace bug stippling symptoms on Azalea leaves. (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)
![Azalea lace bug frass spots & egg laying](https://plant-pest-advisory.rutgers.edu/wp-content/uploads/2023/06/aaaa-Lace-Bug-Azalea-2-Lace-Bug-Signs.jpg)
Azalea leaf undersides with frass spots & egg laying along mid-rib. (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)
When found, use horticultural oil (only if a spray can contact the back of the leaves), or acephate (Orthene) if the shrub is too dense to allow effective use of oil. Imidacloprid (Merit) applied to soils now may require 1-2 weeks before they begin to control this second generation or the beginning of the third generation (longer if soils are dry). Chlorantraniliprole is a reduced-risk insecticide that can be effective against lace bugs. Remember that stressed azaleas in full sun are more prone to lace bugs. Also, & more importantly, predators will be fewer in full-sun locations.
![Azalea lace bug adult](https://plant-pest-advisory.rutgers.edu/wp-content/uploads/2023/06/aaaa-Lace-Bug-Azalea-3-adult.jpg)
Azalea lace bug adult with oval shaped wings. Lace bug species having oval shaped wings will only feed on broad-leaf evergreens. (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)
The Landscape Pest Notes for Late June 2023 in addition to the azalea lace bugs also includes information & photographs of oak spider mites, two-spotted spider mites, pine spittlebugs, mimosa webworms, various soft scales, white prunicola scales, red-headed flea beetles & tree species prone to mid-season leaf drop.
Nursery Pest and Disease Update 6/15/2023
In this edition:
- Insects:
- MORE Scale crawlers emerging
- Borers
- Beetles
- Diseases:
- Oomycete root diseases (Phytophthora, Pythium, Phytopythium)
- Leaf spots / foliage diseases
- Boxwood Blight – reminder
- Virus observations
- Nutrient Management
- Managing Soluble Salts by monitoring EC
- Plant Tissue analysis
- Plant Spotlight:
- American Holly (Ilex opaca)
- Cumberland Nursery / NJNLA – Twilight: tonight (6/15) for NURSERYMEN ONLY (contact twaller@njaes.rutgers.edu or 856-451-2800 Ext. 1. for details)
Please click “read more” below to get updates on pests, diseases, and other important resources for the week of 6/15/2023.
Got leaves?
Have you taken a look at your sycamore lately? Seeing any leaves this spring? Looks like a little problem!
![brown, angular leaf spots on plane tree leaves](https://plant-pest-advisory.rutgers.edu/wp-content/uploads/2023/06/image1-31-300x197.jpeg)
Classic angular leaf spot and twig blight of sycamore anthracnose. Photo: Richard Buckley, Rutgers PDL
Samples of deciduous shade trees diagnosed with anthracnose have steadily found their way into Rutgers Plant Diagnostic Laboratory this spring. Anthracnose is a common fungal disease of shade trees that results in angular leaf spots, cupping or curling of leaves, and premature defoliation. Green stems and twigs can become infected, causing twigs to dieback and overwintering cankers to form. We’ve had samples of sycamore and London plane tree, but have also had ash, beech, maple and a bunch of oaks.
The fungi responsible for anthracnose in shade trees are all unique. The fungus that attacks sycamore is not the same as the fungi that cause ash, beech, dogwood, maple, or oak anthracnose. Each tree species has a specific fungus causing its own anthracnose disease, so for example, the beech anthracnose fungus does not infect oaks and the oak anthracnose fungus does not infect maples and so on.
![brown, angular spots on silver maple leaves](https://plant-pest-advisory.rutgers.edu/wp-content/uploads/2023/06/image3-35-300x200.jpeg)
Marginal necrosis and irregularly-shaped, angular leaf spots on silver maple (Acer saccharinum). Photo: Sabrina Tirpak, Rutgers PDL
Infections by anthracnose causing fungi are favored by cool, wet conditions during the budbreak period in the spring. When the weather favors one of these fungi, it generally favors all of them, so we see the disease to some degree on many different hosts. Anthracnose fungi survive winter in buds, small twig cankers, or fallen leaves depending on which types of trees and fungi are involved. In the spring, the spores are moved by wind and water to newly forming leaves. The longer the weather conditions remain cool and wet, the more damage one can expect. Once the weather becomes dry and the leaves mature, the disease cycle ends and the tree will replace lost leaves with new ones.
Anthracnose can cause a very visible leaf lesion, and depending on the fungus/tree species dynamic, may defoliate the tree. Sycamore anthracnose causes a very significant defoliation, while beech anthracnose rarely does. Furthermore, it is not uncommon for the causal fungus to kill the buds before they open in the spring. It’s also not uncommon for the fungus to kill new green stems and twigs. Although these diseases often seem severe, they have little long-term impact on overall tree health. Leaves and buds damaged early in the season are often replaced by mid-summer.
![distorted oak leaves with small spots](https://plant-pest-advisory.rutgers.edu/wp-content/uploads/2023/06/image5-39-300x200.jpeg)
Small spots with yellow borders and distorted leaves, caused by oak anthracnose. Photo: Sabrina Tirpak, Rutgers PDL
So, what do we do about anthracnose? Not much, really! Rake and remove fallen leaves. Improve plant vigor with fertilization and irrigation in times of drought, and prune all of the dead and dying limbs. Fungicides can be used to prevent the problem in high-value trees. Begin treatments at budbreak to protect the new growth and repeat the treatments 2-3 times at the label specified intervals. Proper timing and good coverage are essential, which will necessitate a licensed professional applicator to make the applications.
By the way, it is too late for fungicide protection this season!
Fungal diseases in most ornamental plants can be prevented with applications of one or a combination of the following active ingredients: FRAC M3 mancozeb; FRAC M5 chlorothalonil; FRAC 1 thiophanate-methyl; FRAC 3 metconazole, myclobutanil, propiconazole, tebuconazole, triademefon, triflumizole; FRAC 7 boscalid, flutolanil, oxycarboxin; FRAC 11 azoxystrobin, fluoxastrobin, kresoxim-methyl, pyraclostrobin, trifloxystrobin; FRAC 12 fludioxonil; and/or FRAC 19 polyoxin-D. Be sure to follow all label specifications for the host plant, the specific diseases controlled, as well as rates, dilution, and timing.
Time to Control Yellow Nutsedge
Now is the ideal time to control yellow nutsedge (Cyperus esculentus). This plant is a perennial that grows best during the heat of summer and survives the winter through underground tubers. While the drought may have limited nutsedge emergence in unirrigated areas, it is visible and rapidly growing in irrigated beds and lawns. Yellow nutsedge […]
2023 Spotted Lanternfly Tracking Survey
Rutgers NJAES Wine Grape Extension, in association with Penn State Extension Grape and Wine Team, is calling on those who own, operate, or manage a farm or vineyard in the New Jersey region to participate in a survey that aims to track the spread and severity of nymph and adult spotted lanternfly populations during the 2023 season. The data collected will provide insights into the distribution patterns of both nymph and adult SLF within and outside vineyards, enabling growers and researchers to better understand this invasive pest’s potential impact on agriculture in the Mid-Atlantic region. [Read more…]