Environment Canada is calling for continued cloud and showers for today and tonight and Saturday morning. It is supposed to start clearing up on Saturday afternoon/evening and Sunday is supposed to be much warmer and sunny (24-26oC).
Growing Degree Day accumulations to the end of Thursday, July 7 (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: 395 / 711 | Oshawa: 414 / 745 | Hamilton RBG: 453 / 815 | |
| Vineland Stn: 507 / 913 | London CS: 504 / 907 | Windsor A: 591 / 1064 | |
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
Growers’ Research Auction, July 14
This year’s auction will be held at Blue Sky Nursery in Beamsville (1 mile east of Beamsville on Regional Rd 81). http://www.horttrades.com/sector/growers
If you are growing ornamentals in containers, now is a good time to check EC and pH. Where pH is creeping up past 7.0, you may want to do some monitoring for interveinal chlorosis (green veins with yellow tissue in between) on woody and herbaceous crops. Many nursery ornamentals cannot get needed micronutrients at high pH and suffer deficiencies of Iron (Fe) and Manganese (Mn), [not Magnesium (Mg)]. If you are seeing chlorosis and media pH is alkaline, try supplementing with chelated Fe/Mn products that are formulated for greenhouse and nursery crops. 2-3 foliar applications should help crops green up quickly. Drenches are much longer lasting but more labour intensive. Chlorosis on Syringa and Hydrangea is often an indication of high pH in the media. Also, test your irrigation water for pH and level of bicarbonates at a commercial lab. The bicarbonates in your irrigation water are driving the pH up in the container media – you need to know what level those bicarbonates are at (<150 ppm is optimal).
Alkaline water (>pH 7.0) that has a high concentration of bicarbonates can actually reduce the action of many pesticide products including: *Cygon*, Dipel, Dylox, Furadan, Imidan, Kelthane, Malathion, Orthene, Pounce, Pyrate, Sevin. It helps to mix the pesticides as close to the application period as possible and to mix only the amount needed for that application (ie. Avoid using tank mixes that have been sitting around for several hours). Ground water sources in southern Ontario can contain high levels of bicarbonates. Try using acidified (e.g. nitric acid, BB5) water or rain water (cistern water) for your sprayer tank.
VARIOUS ORNAMENTALS:
Potato leafhoppers are 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. Adult leafhoppers are winged, very mobile, tiny, pale yellow-green jumping insects that are easily disturbed when you approach infested foliage. It almost looks as though they are being flicked off of the foliage. The soft, succulent growth we had this year was especially susceptible. Leafhopper nymphs are active and appear as tiny, flightless, yellow-green insects that move sideways, very rapidly across the leaf. Leafhoppers (and aphids) suck plant sap from expanding foliage and cause foliage to wilt, become off-coloured and flecked. 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 before damage becomes economically threatening. Leafhoppers are also attracted to yellow sticky cards, for monitoring. Registered insecticides include Tristar and Sevin XLR.
http://dkbdigitaldesigns.com/clm/species/empoasca_fabae
European chafer adults have emerged. Japanese beetle adults have emerged. A preventative application of Intercept (imidacloprid) is registered for white grubs in nursery production. In the field, the application period is June to July (to coincide with egg-laying). To help qualify for the Japanese beetle certification program, an application of Intercept on container stock should be some time between mid-June to July. The cut-off period for Intercept applications to comply with the JB Certification program this year may be as early as July 31st. Nematode applications for white grubs (e.g. European chafer) are not effective at this time. Try timing nematode applications for late August/early September to catch early instar larvae.
DECIDUOUS WOODY AND HERBACEOUS PERENNIALS:
Powdery mildew is prevalent on herbaceous perennials (e.g. Phlox) and some deciduous shrubs (Amelanchier, Physocarpus). 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/
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.
Monitor greenhouse-grown herbaceous perennials for Western Flower Thrips. WFT was detected on Echinacea crops. Success (spinosad) is a good insecticide for WFT but beware because some populations of WFT have become resistant to it. Other biological control products include BotaniGard (Beauveria bassiana, strain GHA) and drenching with the nematode, Steinernema feltiae every 7 days (they kill WFT pupae in soil).
The regulated areas for Emerald Ash Borer have been updated. Check out: http://www.inspection.gc.ca/english/plaveg/pestrava/agrpla/survenqe.shtml
Peach tree borer (Synanthedon exitosa) adults are flying. Look for cankered regions and chewed bark/wood in the lower stems of Prunus x cistena (and other Prunus spp.) as a sign of larval damage. The clearwing moths that emerge resemble wasps. Adults are very much attracted to sticky wing traps that are baited with peach tree borer pheromones. Place pheromone traps out in early-mid June (approximately 390 GDD Base 10oC, ‘Red Prince’ Weigela in full bloom) and monitor for peak flight of adults. You can expect peak egg hatch around 10-14 days later, if you are thinking of treating newly-hatched larvae. The same ‘clearwing moth’ pheromones and traps can be used to monitor for Viburnum borer. Viburnum borer chews the stem (at and below the soil line) and causes significant injury to container grown Viburnum. Viburnum borer adults have started to emerge in container production at this time. To purchase traps, try ordering from IPM suppliers such as www.greatlakesipm.com and www.naturalinsectcontrol.com.
Fall Cankerworm larvae are feeding on deciduous tree leaves (Tilia, Fagus, Quercus). 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 larvae are coming to the end of their feeding period. Populations don’t seem to be very significant in some areas. Some control can be achieved using Bacillus thuringienesis (Dipel, Foray) before larvae are 2.5 cm long (and before they develop a yellow head capsule). Success (spinosad) insecticide can be used at any time in the larval development. 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 prevent females from laying eggs above sticky bands and will attract males to the sticky surface.
Two-spotted spider mites (TSSM) can be found on greenhouse and outdoor grown ornamentals (woody and herbaceous). 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).
EVERGREENS:
Volutella blight is common on boxwood in the propagation phase but this disease can also be found in production and in the landscape. Symptoms include black tissue discolouration along stems, tiny orange cushion-like fruiting structures and tip dieback and browning. Although the disease is worse in propagation zones, it can also be found in field production in moderate amounts. Volutella sporulates in field production in mid-late spring and early summer. Care should be taken to avoid introducing Volutella blight through cuttings from infected plants. Remember, Volutella is often associated with wounds, keep the mother plants protected with fungicides once any pruning or cuttings are taken.
Look for green larvae of yellow-headed spruce sawfly. There are several insecticides registered including Dragnet, Dylox, Pounce and Success to target young larvae. Larvae are green with lighter longitudinal stripes, yellow-brown heads. This is a significant pest of spruce in York region and has caused significant damage to spruce trees. http://www.dkbdigitaldesigns.com/clm/species/pikonema_alaskensis
Pine false webworm larvae may still be feeding on the foliage of white pine. 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.
Spruce budworm (Choristoneura fumiferana) may still be found on the new growth of spruce at this time. In spring, the early instar larvae feed on male flowers and may mine buds and needles. Older larvae feed on expanding shoots, destroying them before they can fully elongate. The small, green larvae were detected because of small patches of browned foliage that had tiny nests made of shoots wrapped together by silk. Larvae can cause defoliation and also browning of the needles. B.t. (Dipel) is an excellent biological insecticide for suppressing spruce budworm populations in mid-late spring.
Cedar leaf miner adults, the tiny silvery-white moths have appeared on foliage in the southwest. Tear along the margin of green and brown tissue and check for the presence of tiny, brown pupa or just empty tissue (to confirm CLM is the cause of the browning foliage). It is likely too late to prune out infested foliage. Foliar applications of systemic insecticides (to target larvae) are much more effective when applied to young larvae (early-mid August). If no larvae can be found and interior tissue seems to be intact, CLM is not likely the cause of foliar damage (winter desiccation may be suspect).
White pine weevil larvae are white, legless larvae feeding inside the terminal of pine and spruce, causing them to wilt, flat and turn brown. Larvae will be pupating soon. Insecticide applications are futile at this point but do inspect white pine, Norway and Serbian spruce for wilting or hooking terminals. Prune out infested leaders and destroy them ASAP to reduce population of next generation adults.
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. 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 will have to wait for late summer/early autumn.
Taxus or Fletcher Scale crawlers are active on twigs and foliage of Thuja and Taxus. Look for tiny, white-clear crawlers on foliage (you will need a hand lens to see them). Since crawler hatch is staggered, two-three applications of insecticides during the crawler stage will give some good management of this pest.
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 (visible mainly with hand lens). 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-july-8-2011.html#sthash.X76tm6js.dpuf
