Environment Canada is calling for continued warm, sunny weather and showers for the beginning Sunday and running into the beginning of next week.
Growing Degree Day accumulations to the end of Thursday, Aug 11 (GDD 10oC / GDD 50oF). (Courtesy of Environment Canada). These numbers are only a guide for monitoring purposes. The temperatures at your production facility can vary significantly from the nearest weather station.
| Borden: 814 / 1465 | Oshawa: 855 / 1539 | Hamilton RBG: 932 / 1678 | |
| Vineland Stn: 1004/ 1807 | London CS: 975/ 1755 | Windsor A: 1163 / 2093 | |
PLEASE NOTE: The Following Pesticide Recommendations are meant for Exception Uses (e.g. agriculture) under the Cosmetic Pesticide Ban unless the active ingredient is listed under Class 11 pesticides in Ontario Regulation 63/09, effective April 22, 2009. www.ontario.ca/pesticides
HOLD the DATE! Thursday, September 15. Nursery Growers Annual Summer Tour. This year the group will be doing a local tour of horticultural operations east of Toronto. More details to follow.
Nursery-Landscape Insect Pest ID: Dave Cheung��s Common Pests of Nursery-Landscape database is available online. Check out www.dkbdigitaldesigns.com/clm
Weed Identification ONLINE: http://www.weedinfo.ca/home.php
Yellowing and sudden leaf drop has been reported on deciduous trees in the landscape and also on some crops in the nursery (e.g. Euonymus) and also some trees in the landscape (e.g. Betula, Acer). Some of the leaf drop is likely in response to extreme heat and is more prevalent in those areas not receiving as much precipitation. In some cases, spring diseases such as anthracnose have been linked to the dropped leaves. It is a survival mechanism of the plant and in most cases, does not lead to dieback.
VARIOUS ORNAMENTALS:
Potato leafhoppers are still feeding. Monitor for leafhoppers (such as potato leafhopper) on nursery crops such as Caragana, and Acer (platanoides, saccharum), especially after forage crops have been cut on neighbouring farms. Leafhoppers are only a concern where new leaves are emerging. Damage on expanded, hardened off leaves is not significant. Potato leafhoppers are especially damaging because they cause foliage to become stunted and deformed, with brown-black margins (�°hopper burn��). Leafhopper injury also appears as bronzing or stippling on more mature leaves. Monitor populations and treat with insecticides where new foliage is emerging. Leafhoppers are also attracted to yellow sticky cards, for monitoring. Registered insecticides include Tristar and Sevin XLR.
http://dkbdigitaldesigns.com/clm/species/empoasca_fabae
This is a pretty heavy year for Japanese beetle adults. Many areas are experiencing high volumes of beetles and heavy feeding pressure. Japanese beetle traps do work but the pheromones may actually attract in more beetles than you would see without traps present so place traps well away from hosts (Rosa, Prunus, Tilia, Syringa, Ulmus etc.) and be vigilant about emptying traps. Contact insecticides are registered for this pest in the nursery.
DECIDUOUS WOODY AND HERBACEOUS PERENNIALS:
Monitor for common leaf diseases such as leaf spot and anthracnose on herbaceous perennials and deciduous shrubs (Rosa, Prunus, Cornus) and deciduous trees. These leaf diseases are more prevalent under late-day irrigation since foliage does not dry off before the evening, prolonging the leaf wetness period and encouraging disease sporulation and infection. Keep disease-prone ornamentals on a strict, mid-morning watering schedule to reduce leaf wetness periods and you will notice that the next flush of growth is much nicer. There are several different fungicides labelled for foliar diseases, including Daconil, Dithane, Copper, Nova, Banner Maxx, Pristine (watch phyto on Physocarpus, Euonymous) and Rhapsody (a biological).
Powdery mildew is prevalent on herbaceous perennials (e.g. Phlox, Rudbeckia) and some deciduous shrubs (Amelanchier, Physocarpus, Rosa). There are several fungicides registered for powdery mildew (Serenade/Rhapsody, Nova, Banner, Compass) but they work best as preventative and will not cure a moderate-heavy infection. Also available this year for the home garden is the biological, Serenade Garden. This product is available as a ready-to-use home garden product. https://www.planetnatural.com/product/serenade-garden-disease-control/
Take a close look at the foliage of Norway, silver and red maples for halos that are filled in with tiny, black spots. This is tar spot on maple. The tiny, black, tar-like spots that make up the larger circular black lesion are the fruiting structures that will produce spores next spring). Fungicides are ineffective at this time of year. The lesions show up so late in the season that they have little effect on tree health, but may be a symptom that the tree is under stress.
Fall webworm larvae are starting to feed on trees. We��ve seen them recently on Betula (birch) and Ribes (current), they are also common on Fraxinus (ash) and Juglans (esp. black walnut). Look for webbed tents on the ends of branches with fuzzy, cr��me-coloured caterpillars inside. The tents can be easily pruned out and destroyed (e.g. squished). Pruning out infested branches can be quite effective right now since there are multiple generations of this pest. Chemical pesticides may give some reduction in webworm populations but it is very difficult to get past that web. Keep in mind that many predators, parasites and pathogens attack fall webworm. Damage from the fall webworm is usually insignificant to tree health, late in the season. Telescoping pruners can be an excellent tool for IPM in the landscape.
Are you seeing strange growths on the leaves of deciduous trees and shrubs? There are several different kinds of leaf galls on ornamental woody plants and the vast majority are completely benign in terms of plant health. I��ve had lots of questions about strange bumps (white, pink, red, green) on oak, ash maple leaves and velvety fuzz (red to orange) on various plants (including maple). Many of these leaf galls are inhabited by immature, tiny wasps, mites and midges. Take a good look at the leaf, if the tissue is still green and its attached to the tree; chances are the gall-forming insect isn��t detrimental to the tree. An exception to this rule are some oak twig galls (gouty, horned), which cause twig dieback.
Various species of aphids (e.g. green peach aphid, melon aphid, foxglove aphid) may still active on deciduous and broadleaf woody and herbaceous plants (spiraea, hosta) in the greenhouse, polyhouse and outdoor production. According to our nursery scout, the heat has enabled populations to explode. Because of the earlier cool weather, foliage is much tender and aphid populations are thriving. Biocontrol organisms are available to help suppress aphid populations in protected crops (midge: Aphidoletes and wasp: Aphidius). Insecticides registered for aphids in nursery production include: Tristar, Endeavor. Insecticide applications can be very effective where even coverage can be achieved.
The regulated areas for Emerald Ash Borer can be found at: http://www.inspection.gc.ca/english/plaveg/pestrava/agrpla/survenqe.shtml
Magnolia scale crawlers are starting to settle on permanent feeding sites on the undersides of branches. They a tiny, dark, flat scales about 1-2 mm long. If you want to try insecticides against the crawler stage, make sure you are making at least 3 repeated applications, 7 days apart. This will have much better knockdown since crawler emergence is staggered. Insecticidal soap and the summer rate of horticultural oils should give good knock down. Malathion, Orthene and Sevin are registered for this pest in the nursery.
Beech Scale crawlers will be hatching soon (from early August to mid-September). Adult females are covered in a white, wooly mass when mature and so they are easy to monitor this time of year. Beech scale can be found on the bark of large beech trees (�� 40cm DBH), mostly on the trunk and on the major limbs. Although the scale insect does not kill the tree, beech scale seems to predispose the tree to other problems and create wound sites that facilitate the entry of beech bark disease (Nectria coccinea var. faginata). Beech bark disease is a devastating fungal disease that has caused the death of several native and introduced beech trees in Ontario. So far, the scale and the disease have been found in beech forests throughout much of southern Ontario (including cottage country). Monitor scale populations for crawlers and treat crawlers about 3 times, every 7-10 days to target staggered emergence. Use insecticidal soap and Landscape Oil or other registered chemical insecticides when peak hatch occurs, in the next couple of weeks or so. Fall and spring (dormant) applications of horticultural oil may also reduce beech scale populations.
Two-spotted spider mites (TSSM) can be found on greenhouse and outdoor grown ornamentals (woody and herbaceous). This week our Nursery Scout found them feeding on Buddleia sp and Sambucus. Use your hand lens to see tiny, clear bodied mites with dark regions (may be faint black) on their backs. These mites are small but the damage is significant so catch them early. Miticides registered for this mite in the greenhouse include: DynoMite, Vendex, Shuttle, Floramite, Avid and Kelthane. Apollo is registered in outdoor nursery crops to knock down the egg stage and newly hatched nymphs. In the greenhouse, biocontrol agents should be brought in to coincide with the first sign of TSSM. Phytoseiulus persimilis is a predatory mite that feeds on TSSM when temperatures are below 26oC and it is a good choice when TSSM populations are low-moderate. Amblyseius californicus is a predatory mite that can be brought in ahead of TSSM appearance (because it can find other sources of food).
Look for honeylocust spider mite on cultivated honeylocust (Gleditsia). These orange mites can be found feeding on leaf undersides in late summer. Where damage is causing leaf drop and dieback in the nursery, a miticide application may be warranted.
EVERGREENS:
For those of you growing Scots and Austrian pine, Lophodermium needlecast could be starting to sporulate in your production area. Look for brown, fallen needles with tiny, black football-shaped fruiting bodies running the length of the needle. Where more than 10% of the trees are infested, Michigan State University recommends fungicide applications during warm, humid weather in August and September. Registered fungicides to help protect healthy tissue include Copper spray, Daconil, Dithane and Manzate.
Cedar leaf miner eggs and larvae are found inside the tips of new growth at this time. Now is a great time to shear white cedar hedges and specimen trees that have previously been infested with this leaf miner. Larvae inside clippings will not survive to complete their life cycle. Applications of systemic insecticides (to target larvae) are effective when applied to young larvae (early-mid August).
Monitor for black vine weevil ADULTS in the FIELD and LANDSCAPE for Rhododendron, Taxus, Thuja and Euonymus. It��s too late for applications of nematodes in the field/landscape. Strawberry root weevil can also be a problem in field production of evergreens, adults have emerged. Signs of strawberry root weevil adults include brown, flagging shoot tips (and small girdling marks at the base of the flagged shoot) on Thuja (eastern white cedar). To scout for adult weevils, place a tarp or large piece of card board under the tree, shake branches vigorously and look for brown-black weevils �°playing dead��. Insecticides for adult weevils in the nursery include Pounce, Sevin and Thiodan. Remember, adult weevils feed at night. Spray insecticides in late evening to target adults and reduce UV degradation (e.g. Pounce).
Black vine weevil adults are active in CONTAINER production and laying their eggs. Where black vine weevil larvae are a problem in CONTAINER PRODUCTION (e.g. perennials, evergreens), insecticide applications can be made to target the adult stage. Nematode applications for larvae should begin in September.
Monitor for spruce spider mites on conifers with a history of mite damage. Newly hatched spruce spider mites are brown with a black back and very tiny with 6 legs (visible mainly with hand lens). Adults are a little larger, darker and have 8 legs. Monitor lower branches, this is where most of the feeding damage is done, on the morning sun side of the tree. Mite injury looks like bronzing (tiny, yellow flecks on the needle seen through hand lens). Miticide applications (e.g. Floramite, Kanemite, Vendex) are recommended where populations are at damaging levels.
– See more at: https://lawnsavers.com/nursery-and-landscape-report-2011/nursery-and-landscape-report-for-august-12-2011.html#sthash.uhJMxzso.dpuf
