Environment Canada is calling for continued warm, sunny weather with high��s in the mid-high 20��s. This beautiful weather is expected to run into the beginning of next week.
Growing Degree Day accumulations to the end of Thursday, Aug 25 (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: 941 / 1694 | Oshawa: 1001 / 1802 | Hamilton RBG: 1096 / 1973 | |
| Vineland Stn: 1175/ 2115 | London CS: 1117/2011 | Windsor A: 1334 / 2401 | |
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: https://www.weedinfo.ca/
Early leaf drop and fall colour is visible on trees and shrubs in the landscape. This is especially true of woody plants on roadsides, high sandy knolls or compacted sites. Some areas of the province have received very little precipitation during the many heat waves this summer. Some plants are going into senescence early as a stress response. It happens every year.
Now is the time to start putting out rodent bait for vole control in the nursery and landscape (especially where container plants are pot tight). With all the seeds and fruit available this time of year, rodents are beginning to breed heavily and build up their numbers for the winter months ahead. By putting out bait in September, you can prevent populations from getting out of control. Place bait stations in areas known to be infested such as grassy fence rows, weedy patches and walkways between containers and polyhouse frames. Try to have about 10 bait stations per acre of production area. Remember to rotate zinc phosphide baits with other baits (e.g. bromidialone, brodifacaum, defethalone) since the voles will become bait shy with repeated use of zinc phosphide. Where large areas of field production exist, broadcast application of baits may give some control where tunnels and past damage are evident.
VARIOUS ORNAMENTALS:
Bagworm (Thyridopteryx ephemeraeformis) has been reported widely in the neighbouring United States. This is a moth whose caterpillar stage feeds on foliage (spring-summer) from inside a protective �°case�� that looks like it was made out of tiny bits of wood. Look for damage on cedar, spruce, and several different deciduous hosts including honeylocust and crabapple. Foliage will turn brown and become quite sparse. At this time, �°bags�� can be found on branch tips and resemble small conifer cones. The bags can be picked off and destroyed in the fall to prevent the next generation from hatching next spring. Please drop me an email if you are seeing this pest.
This has been a pretty heavy year for Japanese beetle adults. Many areas have experienced high volumes of beetles and heavy feeding pressure. The adult stage is starting to die off now and most eggs have been laid. 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.
Black vine weevil larvae will be hatching and feeding on roots in CONTAINER production. Where black vine weevil larvae are a problem in CONTAINER PRODUCTION (e.g. perennials, evergreens), nematode applications for larvae should begin in September. A good species choice is Heterohabditis bacteriophora. This species has shown excellent efficacy in container production trials.
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. It��s getting a bit late in the season for fungicides, you should only consider fungicides on crops where new growth is emerging. 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. This late in the season, it is best to wait until plants finish blooming and remove infested shoots to prevent the disease from overwintering in the garden.
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 feeding on trees. We��ve seen them on Betula (birch) and Ribes (current), they are also common on Fraxinus (ash) and Juglans (esp. black walnut) and Prunus (cherry). 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. Insecticides (e.g. B.t.) 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) where new growth is still emerging. Biocontrol organisms are available to help suppress aphid populations in protected crops (midge: Aphidoletes and wasp: Aphidius). This late in the season, there are several predatory and parasitic beneficial insects that are feeding on aphids. Where aphids are economically threatening, insecticides registered for aphids in nursery production include: Tristar, Endeavor. Insecticide applications can be very effective where good 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 settling on permanent feeding sites on the undersides of branches. They are 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 Viburnum, Hydrangea, Buddleia, Cercis, Sorbus, Salix, . 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.
Maple Spider mites (Oligonychus aceris) were found on various maple trees (Acer saccharum, rubrum, and hybrids). The populations were moderate, with an average of 4.3 mites a tree in 10 trees observed. The eggs hatch in the spring and will feed on the undersides of the leaves. There may be several generations throughout the growing season. The adult is dark red or black with a white marking at the top of the abdomen near the head. Mites can cause a lot of damage (speckling and bronzing of the leaf) when populations get high, a miticide may be warranted. Mites will be laying eggs near the bud for next year��s growth soon.
EVERGREENS:
For those of you growing Scots and Austrian pine, Lophodermium needlecast could be sporulations 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 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) may be effective when applied to young larvae (early-mid August) and are registered in the nursery.
Taxus or Fletcher Scale (Parthenolecanium fletcheri) crawlers may be migrating around foliage of Thuja and Taxus. Look for honeydew, black sooty mould and small, brown bumps (dead adult females) on foliage. The nymphs are pale tan, flattened, and about 1-2 mm long. Applications of insecticides are not nearly as effective against these older nymphs as they were for the crawlers. In the nursery, systemic insecticides may be warranted where populations are significant.
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. We can find both life stages at this time. Monitor lower branches, this is where most of the feeding damage is done, on the east side of the tree. Shake branches vigorously over a sheet of white paper (on a clip board) and count mites. We were finding 5 mites per 8cm circle of white paper in one infested block this week. 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-26-2011.html#sthash.LlYNrrxD.dpuf
