It’s usually somewhere around this time of early summer that we have a chance to take a breath. Its been another intense, extreme weathered spring and YOU deserve some time off for good behavior. For me, that’s spending time in nature, for others, it’s Netflix. If you can even remember what it is you like to do, get going and go do it. Before you forget how.
Plant Phenology indicators this week. (400-500 GDD Base 10oC) : Catalpa speciosa (full bloom), Syringa reticulata (late bloom), Sambucus canadensis (early bloom). Plant phenology models for IPM can be found starting on pg. 39 of OMAFRA Guide 841, Guide to Nursery and Landscape Plant Production & IPM. Many of these models are based on Donald Orton’s COINCIDE.
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.
The Crop Protection Guide for Nursery and Landscape Plants (OMAFRA publication 840) contains the crop pest recommendations for nursery and landscape plants that was previously found in publication 383. Publication 840 is a .pdf file, accessible online and on cd.
Pest recommendations can also be found on our online, searchable database: www.nurserytracker.com. Check out NurseryTracker on your phone or tablet!!!
Nursery-Landscape Insect Pest ID: Dave Cheung’s Common Pests of Nursery-Landscape database to help ID your problem pests.
Japanese beetle adults are taking flight. Adults are just starting to emerge in southern Ontario. European chafer adults should be emerging any day now. Look for these shiny green and copper beetles feeding on grapes, roses and other flowers. Where possible, knock adults into a bucket of soapy water (to kill them). Several insecticides are registered for the adults, including Sevin XLR.
Have white grubs (e.g. European chafer, June beetle) or Japanese Beetle phytosanitary restrictions been an issue at your nursery? Preventative applications of Intercept (imidacloprid) and Acelepryn (chlorantraniliprole) are registered for white grubs in nursery production and the application period begins now.
have emerged and are feeding on various evergreen and deciduous hosts in field and container grown ornamentals. Feeding from the larval stage is much more damaging so reducing populations of adults, can help reduce future populations of larvae.
Look for Strawberry root weevil adults in spruce, eastern white cedar and sometimes in juniper. SRW’s will chew notches in small twigs, girdling them and causing the shoots to turn brown.
Look for adult black vine weevils in yews, eastern white cedar and euonymus. BVW adults will chew notches in the margins of leaves.
Adults can be managed in nursery production with insecticides such as Actara, Scimitar SC, Sevin and Thionex. Monitor for adults by placing out wet boards or burlap on the ground underneath the crop. Monitor for weevils under the board/burlap during the day. Alternatively you can shake the canopy onto a light coloured sheet and count adults that fall on the sheet.
Lecanium scale (Lecanium corni) on deciduous trees such as oak and Fletcher scale (Lecanium fletcheri) on Yew and eastern white cedar CRAWLERS are emerging and starting to feed on new growth. Pick off adult scales and look for eggs and crawlers underneath. Crawlers (see video) hatch and emerge over a period of a few weeks so multiple applications of insecticide is needed. Monitor for crawlers (eggs with legs) and treat with 3 times, about 7-10 days apart. Insecticidal soap, summer rate of horticultural oil, Pounce and others are registered for this pest.
Euonymus scale crawlers are settling as nymphs in container production but are still active in the landscape. Bright ORANGE crawlers (see video) hatch and emerge from scale shells over a period of a few weeks so multiple applications of insecticide is needed. Monitor for ORANGE crawlers (eggs with legs) and treat with 3 times, about 7-10 days apart. Insecticidal soap, summer rate of horticultural oil, Pounce and others are registered for this pest.
DECIDUOUS WOODY AND HERBACEOUS PERENNIALS:
We have seen more powdery mildew on deciduous flowering shrubs (Amelanchier, Rosa) and herbaceous perennials. Monitor for white, powdery residue on the tops and bottoms of leaves. Protect new foliage with fungicide applications (e.g. Switch, Milstop, Regalia (bio)) where the history of disease pressure is moderate to high.
Peach tree borer (Synanthedon exitosa) adults are flying still. Look for cankered regions and chewed bark/wood in the lower stems of Prunus (e.g. Prunus x cistena) as a sign of larval damage. These clear-wing moths resemble wasps and adult males are attracted to pheromone baited sticky traps. Bark applications of insecticides should finishing up at this time Some growers are trying soil drench applications of beneficial nematodes, S.c., (Steinernema carpocapsae) after peak adult flight, as a biological way to suppress hatching larvae.
Injectable insecticides may be used to protect ash trees from new infestations of Emerald Ash Borer (Agrilus planipennis). Trees must be actively transpiring in order to maximize insecticide uptake into the cambium. Registered injectable insecticide products include: AceCap 97, Confidor 200 SL and Tree-Azin. Check out the Management Strategy for Emerald Ash Borer and Bronze Birch Borer at: http://www.omafra.gov.on.ca/english/crops/insects/eab-bbb-manage.htm. Emerald ash borer adults start to emerge when the black locust (Robinia pseudoacacia) are blooming.
Potato leafhoppers NYMPHS and ADULTS are feeding on woody nursery stock. Monitor for potato leafhopper on nursery crops such as Acer (platanoides, saccharum), Quercus and Ostrya. Adults will fly away quickly but nymphs are about 2 mm long and scuttle SIDEWAYS, rather quickly, across the leaf and to the other side (they don’t have wings). Susceptible crops are those that are flushing new leaves (leafhopper’s favourite food source). Older, hardened off foliage is not usually as susceptible. Leafhoppers (and aphids) suck plant sap from soft, expanding foliage and cause foliage and stems/petioles to wilt, turn brown/black (‘Hopper Burn”) and become stunted and malformed.
Older, hardened off foliage will become flecked from potato leafhopper feeding but younger foliage is more severely damaged. Monitor populations and treat where new foliage is emerging. Leafhoppers are also attracted to yellow sticky cards, for monitoring. Registered insecticides include Tristar and Sevin XLR.
Gypsy moth larvae are in their heaviest feeding period as they are late instar larvae at this time. The love to hide during the day (in bark crevices and underside of twigs, leaves) and can often be found on oak, elm, beech etc. and also Colorado spruce. Success is a good lower toxicity choice but many broad spectrum insecticides will give good knockdown if it can reach the elusive larvae. Sticky bands around trunks during the July flight period will help trap female Gypsy moths and will attract males to the sticky surface as well.
Two-spotted spider mites (TSSM) is feeding on several deciduous and herbaceous plants, especially in container production. Use your hand lens to see tiny, clear bodied mites with dark regions (may be faint black) on their backs. The hotter it is, the faster they reproduce.
Two spotted spider mites are small but the damage is significant so catch them early. Miticides registered for this mite in the greenhouse include: DynoMite, Vendex, Kanemite, Floramite, Avid. 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).
Where new foliage has not hardened off yet, monitor for needlecast and blight diseases on conifers 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, Banner Maxx, 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..
Look for crooked, wilting and browning terminal shoots on pine and spruce with sap weeping and cankered-looking bark, it could be boring larvae from white pine weevil.
Where appropriate, slice into bark and look for tiny, fat, white, legless grubs feeding in the cambium.
Insecticide control for white pine weevil is too late at this point, prune out and destroy (don’t leave the infested terminals on the ground)
all symptomatic terminals and train a new leader.
Look for larvae (15 mm long) of Yellow-headed spruce sawfly feeding on tender new needles of spruce (e.g. Colorado spruce) in the landscape. Larvae are green with lighter longitudinal stripes, yellow-brown heads. There are several insecticides registered including Dragnet, Dylox, Pounce and Success to target young larvae. This is a damaging pest of spruce in the GTA and has caused significant damage to spruce trees in the landscape. Just remember, the bigger they get, the harder they fall.
Monitor for nymphs and adults of spruce spider mite on conifers with a history of mite damage. Spruce spider mite nymphs and adults are brown with black backs and found on new foliage this time of year (Juniperus, Thuja, Picea etc.). Miticides registered for SSM include Floramite and Kanemite. Miticides may be required where pest pressure is moderate to heavy (container grown conifers with overhead irrigation).