Environment Canada is calling for sunny, cloudy conditions with highs in the range of 15-19oC today and Saturday, a little warmer on Sunday. Night time lows are forecasted to be above freezing in most areas of southern Ontario. Winds will be out of the NW at ~20km/hr.
Growing Degree Day accumulations haven’t really changed since last week. These are to the end of Thursday, May 13 (GDD 10oC / GDD 50oF). These numbers are only a guide for monitoring purposes. The temperatures at your production facility can vary significantly from the nearest weather station. Check out: https://climate.weather.gc.ca/?url=http%3A%2F%2Fclimate.weather.gc.ca
| Peterborough: 61 / 110 | Hamilton RBG: 91 / 164 | |
| Vineland Stn: 73 / 131 | London CS: 97 / 175 | Windsor R: 144 / 260 |
Growers’ Research Auction, July 15
Landscape Ontario Milton office (7856 Fifth Line South, below Steeles) will host this year’s Growers’ Group annual fundraiser. All landscape trades are welcome — bring your trailer! The LO Growers Awards of Excellence entries will also be judged and put on the auction block!
Plastic pot, tag and tray recycling!
Bring your plastic pots, tags and trays to Landscape Ontario office in Milton (5th Line South of Steeles) for recycling, from June 28 to July 5. For more information, contact Lorraine Ivanoff at 1-800-265-5656, ext. 2366, or email lorraine@landscapeontario.com.
NEW! Weed ID Online: http://www.weedinfo.ca/home.php
PLEASE NOTE: 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. There is exception from the ban for the use of pesticides to maintain the health of TREES, if certain conditions are met. For more info, you can go to the Ministry of the Environment’s website athttp://www.ontario.ca/pesticides
VARIOUS ORNAMENTALS:
Given the amount of new growth out there yes, we should all be watching the weather closely and preparing plants for protection against freezing. Historically, frequent, low volume overhead irrigation (e.g. small droplet size nozzles designed for frost protection) throughout the coldest hours of the night/morning have been used to reduce freezing injury on new plant tissue. This takes repeated irrigation events, before temps go down to freezing, to keep a film of water on the plants (and under the ice). Water can also be used in early morning to melt ice more quickly and take that stress load off the plant tissue. Insulating cloths (light duty thermal blankets) have also been used quite successfully when secured around plants to hold heat around them during cold temperature events (sometimes in conjunction with irrigation). Fans can also be used to blow cold air off of plants, leaving a void for warmer air to come in (e.g. frost fans in vineyards, polyhouses).
If you are bringing in SOD (Sudden Oak Death, Phytophthora ramorum) host nursery stock from high risk areas, you may want to monitor for SOD symptoms. Camellia, Rhododendron, Viburnum, Pieris, Kalmia and Syringa are considered to be high risk host genera, as they are most common genera found positive for SOD in retail and wholesale nurseries. Fungicides registered for SOD in nurseries include: Acrobat, Chipco Aliette WG and Subdue Maxx. For a complete list of SOD regulated hosts, check out: http://www.inspection.gc.ca/english/plaveg/protect/dir/sodspe.shtml
Monitor for black vine weevil larvae in the FIELD and LANDSCAPE on Rhododendron, Taxus, Thuja and Euonymus. Applications of nematodes, for example (Steinernema kraussei, NemasysL) should have been made by now.
Where black vine weevil larvae are a problem in CONTAINER PRODUCTION (e.g. perennials, evergreens), treatment with Heterohabditis bacteriophora should be completed. Black vine weevil adults will be emerging soon in container production.
DECIDUOUS WOODY AND HERBACEOUS PERENNIALS:
All this rain has stimulated sporulation of cedar-apple rust and cedar-hawthorn rust and branch swellings of pear-trellis rust on Juniper. These slimy, orange projections contain the spores that will infect the alternate Rosaceous hosts: Malus, Crataegus, Amelanchier, Pyrus etc. Apply protectant fungicides (such as Nova) to Rosaceous hosts when the Juniper galls start to sporulate this spring. Note: Nova has some curative action post-infection.
For those of you hoping to protect Norway maples from tar spot this year, fungicide applications should be taking place before precipitation events, until leaves harden off. Fallen leaves from last year’s growth contain fruiting structures that are releasing infective spores during precipitation events. Symptoms of infection will be faint, yellow halos in early July that fill in with small, black spots in July and August.
Dutch Trig is registered for Dutch Elm Disease on Ulmus americana species in Canada. This is a new registration (fall, 2009) that contains a biological organism that induces an immune response to help the tree fight off DED infections. Arbotect-20-S (thiabendazole) is the registered injectable fungicide treatment. Injections should be made on sunny days during leaf emergence to maximize uptake.
Two-spotted spider mites (TSSM) will be starting to show up on greenhouse grown ornamentals (woody and herbaceous) soon. 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. 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).
Elm flea weevil adults may be noticeable on Siberian elm (Ulmus pumila) at this time. They emerge as the leaves are opening and start to feed. Early adult feeding causes small, discrete holes in the leaves. Adults are tiny, reddish brown weevils. They lay their eggs into leaf tissue and the larval stage feed as leafminers in spring and early summer. If you are seeing this pest, please let me know.
We saw adult elm sawflies laying eggs on Siberian elm leaves last week on campus. Eggs hatch in the next couple of weeks and larvae feed as elm leafminers within foliage. Each year, elm leafminer causes significant injury to elm, especially non-native species. Monitor historically-damaged trees and treat with system insecticides where appropriate.
Where honeylocust podgall midge was a problem in the past, monitor trees for reddish eggs on buds and new leaves. Research in Oregon suggests that horticultural oil applications (summer rate) targeting the first couple of egg clutches can help reduce the incidence of pod gall midge. Honeylocust plant bugs can be found feeding on new foliage. This was a significant pest in the last couple of years, treat where there is a history of high population, where appropriate.
Eastern tent caterpillar larvae are coming up to their heavy feeding period. Applications of B.t. (Dipel) should be taking place as soon as possible. Apply B.t. on foliage during the evening hours. Did we lose some caterpillars to the frost event last Sunday night?
Fall Cankerworm larvae will be feeding on deciduous tree leaves soon. Look for green or dark grey “inchworms” feeding on the undersides and edges of leaves. They will strip leaves similar to Gypsy moth larvae (and in fact, the two can often be found feeding on the same tree). Cankerworm larvae are susceptible to Bacillus thuringienesis (Dipel, Foray), spinosad (Success) insecticides, but you will need to make B.t. applications as early in larval development as possible.
Gypsy moth egg masses have hatched. Larvae begin to emerge (Cercis canadensis blooming). Some control can be achieved using Bacillus thuringienesis (Dipel, Foray) in the first 2 weeks after egg hatch. Spinosad (Success) insecticide is a low toxicity choice that is effective during all instars. Some keen homeowners can install a burlap skirt at the base of the tree to create a shady, protected area for larvae to hide during the day (this behaviour usually peaks near the end of May). Homeowners will need to inspect burlap skirts and underlying bark crevices daily (1-3 pm is best) and remove/destroy larvae. Sticky bands around trunks will help intercept females from laying eggs above and will attract males to the sticky surface.
Viburnum leaf beetle larvae are feeding and about 3mm long in the landscape. The larvae are vulnerable to chemical control only during the first 7-10 days after hatch. Larvae feed on the interveinal tissue from the undersides of the leaves, keep that in mind if you are making insecticidal applications. Young larvae are most commonly found on the undersides of the newest leaves.
Birches with a history of bronze birch borer infestation should be pruned by now. Destroy pruned material to prevent emergence of beetles. Betula nigra and its selections have been shown to be quite tolerant to BBB attack.
Emerald ash borer adults will be starting to emerge in the next month or so. TreeAzin (azadirachtin, neem) has an emergency use registration (until August 31) for emerald ash borer on ash. This is an injectable insecticide that is delivered though BioForest’s Ecoject system, to inject insecticides to protect ash trees from this borer. For more information contact BioForest (https://bioforest.ca/en/canada/products/). The regulated areas for Emerald Ash Borer have been updated. Check out:http://www.inspection.gc.ca/english/plaveg/pestrava/agrpla/survenqe.shtml
EVERGREENS & CONIFERS:
Where new foliage is emerging on conifers, monitor for needlecast and blight diseases in the area. Diplodia tip blight on 2 and 3 needled pines and Rhizosphaera needlecast and Stigmina on blue Colorado spruce are our most common needlecast diseases in Ontario. Diplodia tip blight appears as brown, stunted needles at the tips of branches. Rhizosphaera appears as brown-purplish needles from the previous year’s growth, symptomatic needles begin to drop in late spring. Stigmina appears on green and chlorotic needles, but doesn’t always lead to needle drop. To confirm it is Rhizosphaera, look at the undersides of the needles. Those little white dots (stomata) will turn black and the black spots will protrude during sporulation. New, soft growth is especially susceptible to foliar diseases, but infection may also take place later in the season (we don’t know). Where there is a history of damage, treat with registered fungicides (copper oxychloride, Daconil) as buds start to open and protect new foliage. Apply fungicides prior to precipitation events (spore dispersal). Unfortunately, most of these blights and needlecasts can be found sporulating for much of the year.
Pine false webworm may still be found flying and laying their eggs on needles of white pine When eggs hatch, young larvae snip off foliage and make webby nests near the trunk. The larvae clip off more needles and pull them into the webby nest where they feed on them. The larvae feed mainly on older growth and will only eat the current year’s growth when all else has been consumed. The new nests can be dislodged with a strong stream of water.
Where leaf cupping and distortion was a problem last year, look for tiny, orange eggs and newly-hatched nymphs of the boxwood psyllid. The eggs hatch as the new leaves begin to emerge. The nymphs are yellowish-green at first but later secrete a white, waxy substance that can be seen on new foliage and on the nymphs themselves. Treat with insecticides such as insecticidal soap, carbaryl (Sevin) to reduce populations of newly hatched nymphs when new growth appears. Carbaryl is toxic to honeybees so avoid carbaryl applications on plants that are blooming. Where boxwood leafminerwas a problem last year, treat new growth with a systemic insecticide (dimethoate) to limit damage from new generation larvae.
European pine sawfly larvae have hatched. Look for small, green-tan larvae with dark heads clustered against needles. They can be easily destroyed or manually removed this early. A low toxic pesticide choice is Success. Closely examine pine trees and shrubs such as Pinus sylvestris, Pinus mugo, Pinus nigra.
Monitor for nymphs and eggs of spruce spider mite on conifers with a history of mite damage. Spruce spider mite eggs appear as very tiny, round, reddish-brown spheres that adhere to twigs and foliage. SSM nymphs are tan coloured with dark backs, and move at a moderate pace. Use ovicidal products at this time and wait another couple of weeks until egg hatch is complete to use Miticides. Miticides registered for this pest include Kanemite, Floramite and Vendex.
Monitor for Balsam twig aphid STEM MOTHERS on the new shoots of fir, white spruce, Colorado spruce and juniper, they are susceptible to insecticide applications until they are covered in white, waxy filaments (wooliness). These tiny, bluish grey stem mothers (nymphs) can be found feeding on tender, emerging foliage. Apply Diazinon, Malathion or Tristar on warm days (55 to 78 GDD Base 10oC) to target these stem mothers before they produce the next generation of aphids. Photos:
http://www.insectimages.org/browse/subimages.cfm?SUB=321 http://ctrees.cas.psu.edu/pdfs/PestsofTrueFir.pdf
Pine shoot beetle adults may still be laying eggs. The tiny beetles take flight after 2-3 days where temperatures reach 10-12oC. Adults lay eggs underneath the bark of stressed or dead pine trees and stumps. Those larvae will develop later in April and May. Remove brood material (i.e. trap (sentinel) logs, snags, dead/dying trees) before new progeny adults emerge (210 GDD, Base 10oC) to comply with the CFIA. All brood material must be burned, chipped (less than 2cm diameter) or buried (30 cm deep) to comply with CFIA standards.
Taxus or Fletcher Scale nymphs have overwintered on foliage of Thuja and Taxus. Applications of insecticides may give some suppression of this pest but nymphs are quite large now and were more susceptible in mid-to-late summer of last year. Nymphs will be feeding and producing copious amounts of honeydew in the next 4-6 weeks.
Cedar leaf miner larvae have resumed feeding from the inside of leaf scales. Tear along the margin of green and brown tissue and check for the presence of tiny, yellow/green larvae with dark heads (to confirm CLM is the cause of the browning foliage). Infested foliage should be pruned out, collected and destroyed by now as adults are starting to emerge (there are several species of cedar leafminer).
– See more at: https://lawnsavers.com/nursery-and-landscape-report-2010/nursery-and-landscape-report-for-may-14-2010.html#sthash.bsWEvsYU.dpuf
