BLACKLEAF / WITCHES BROOM

Transcription

1 Problem Pests of Fruit Problem Pests Workshop 2017 Black leaf / Witches Broom Saskatoon Berry / Juniper Rust Entomosporium Leaf and Berry Spot Apple Maggot Fireblight Raspberry Cane stuff crown borer, spur/cane blight Botrytis Tarnished Plant Bug Outline Disease / Life cycle Symptoms Conditions Favouring Disease / Insect Development BLACKLEAF / WITCHES BROOM Black Leaf / Witches Broom Apiosporina collinsii Host = Saskatoon berries Tends to be more prevalent in wild stands, in older or neglected orchards, or sporadically in managed orchards Does not tend to have much economic impact and is not typically considered to be lethal to plants Reduces productivity of the orchard 1

2 Management Remove & destroy all infected seedlings, transplants, & branches Prune infected branches 10 to 20 cm below infection site 2

3 Saskatoon Berry Juniper Rust Gymnosporangium nelsonii & other species SASKATOON BERRY / JUNIPER RUST Rust on Saskatoon Firm, spiky outgrowths on leaves or fruit Outgrowths on shoots, stems & leaves MAY JUNE JULY AUGUST Jelly-like Telial horns Spores reinfect Juniper Juniper Rusty outgrowths on fruit Spores infect leaves & fruit Saskatoon Berry 3

4 Conditions Favouring Disease Development Moist or rainy conditions Presence of diseased junipers Avoid planting near native stands of Juniper If junipers are present within 1 2 km, remove infected galls (if possible) Chemical controls are available Botrytis (Gray Mould) Botrytis cinerea BOTRYTIS (GREY MOLD) Attacks various plant parts Botrytis (Gray Mould) (Photo Courtesy MAFRI) Initially, rot is soft and light brown in colour Leaves, fruit, blossoms & blossom stalks covered with light gray growth Off flavoured fruit May develop postharvest Botrytis Fruit Rot - early Botrytis Fruit Rot - late (Photo Courtesy MAFRI) 4

5 Botrytis infected fruit Botrytis Fruit Rot ripe and mature fruit affected Botrytis infected leaf Botrytis infected cane Conditions Favouring Disease Development Shade or dense foliage in the bed or row High humidity / Poor air circulation Extended periods of excessive moisture Cool spring & summer temperatures Lush, succulent growth or older tissues are more susceptible Factors that contribute to soft fruit e.g. excessive N fertility during fruiting Protective fungicide applications from bloom to harvest if conditions are cool, wet Follow appropriate Pre harvest Interval Ensure good straw mulch barrier between berries & soil (strawberries) Avoid bruising fruit Remove infected berries from the field Remove decaying or diseased leaves, fruit & canes Remove spent canes Thin canopy to ensure adequate ventilation Ensure fruit is harvested regularly Avoid over fertilization with Nitrogen ENTOMOSPORIUM LEAF & BERRY SPOT 5

6 Entomosporium Leaf & Berry Spot Entomosporium mespili Most serious disease of Saskatoon berry Entomosporium leaf & berry spot Lesions on leaves various degrees of infection Fruit Symptoms Fruit have watery, greyish lesions Fruit may become discoloured, disfigured, shrivelled or cracked Fruit stalks may become infected Severe infestation results in fruit cracking & shrivelling Conditions Favouring Disease Development High humidity / precipitation and warm temperatures Spores dispersed by precipitation Flourishes from early May through mid July Overwinters where? Distinctive spores of Entomosporium 6

7 Ensure adequate air circulation Pruning Orchard orientation Careful consideration of plant stand density Apply water to the soil surface (not sprinkler applications) Control weeds Apply preventative fungicide sprays Preventative Sprays Timing Flowering stages = White Tip, Petal Drop, Green Fruit (varies with product) Make 1st application after first rain event that occurs 1+ days after flowering (when petals open up) Connected to spore dispersal Preventative Sprays No product provides a cure, only PROTECTION / PREVENTION PRODUCT SELECTION Chemistry/efficacy of products varies somewhat Pre Harvest Interval (PHI) Sets limits on application timing CANE BLIGHT Cane Blight Leptosphaeria coniothyrium Early disease symptoms at wound site Late disease symptoms fruiting body development Dark areas develop up & down from a wound or abrasion site Black, fruiting structures may be visible Blighted Canes Black fruiting structures produce spores that are released during rainy periods Infection begins at a wound site or at an abrasion 7

8 Laterals & leaves wilt Affected canes become brittle & snap off easily Producing canes may die between flowering & fruiting Choose a suitable planting site Use clean planting stock Ensure adequate canopy ventilation through pruning Remove & destroy diseased canes Avoid mechanical injury to canes Registered fungicides may be applied Blighted Canes Didymella applanta Spur Blight SPUR BLIGHT Blighted Spurs Brown or purplish discolouration at point of leaf attachment Discolouration will spread up & down Fungus survives on infected canes Spores are spread by wind and water splash Blighted Spurs 8

9 Leaves may become chlorotic Fruiting bodies may be apparent on the canes Buds may fail to break in the year following infection Spurs/Canes late development Prune out & destroy diseased canes after harvest Control weeds Use clean planting stock Thin canopy to improve canopy ventilation Ensure proper plant spacing Registered fungicides may be applied Fire Blight FIRE BLIGHT Erwinia amylovora Very wide host range There is a strain specific to raspberries that will not infect apples, cherries, Saskatoon berries, etc. Fireblighted branch Wilting of new shoots in characteristic Shepherd s Crook Sudden wilting & browning of blossoms Foliage develops a scorched appearance Bacterial ooze may be seen in humid weather Young fruit may turn brown or black 9

10 Prune out infected canes and branches / shoots (25 45 cm below the lowest point of infection) Avoid succulent growth 2 biological products are registered for suppression of fireblight in Saskatoon berries, caneberries & non bearing apples (nursery stock) APPLE MAGGOT Apple Maggot Rhagoletis pomonella Hosts: Apple, crabapple, hawthorn, sweet cherry, sour/tart cherry, asian & common pear, bitter cherry, common plum, spreading cotoneaster, etc Apple maggot damage on fruit (Photo by www2.gov.bc.ca) Apple maggot adult fly note zigzag pattern on wings (Photo by operationfruitrescue.org) 10

11 Symptoms Larval feeding / burrowing within the fruit results in brown channels Infested fruit is often misshapen and may appear bumpy Black spots, small dimples or depressions may be visible when egg laying has occurred Infested fruit often drops prematurely Management Chemical controls are available for use in commercial operations use in conjunction with monitoring for adults Remove wild plants within 500m of any established orchard Remove and destroy infested fruit from the trees Collect and dispose of dropped apples right after they fall, to prevent larvae from emerging and pupating Sanitation is CRITICAL Lygus lineolaris A.K.A. Lygus Bug Tarnished Plant Bug TARNISHED PLANT BUG One of the most serious & widespread of strawberry pests Wide range of host plant species Tarnished Plant Bug - adult Tarnished Plant Bug nymph (Photo Courtesy MAFRI) Distinctive Triangle Marking Tarnished Plant Bug adult on flowers Tarnished Plant Bug nymph & adult on fruit Tarnished Plant Bug adult (Photo Courtesy MAFRI) 11

12 Tarnished Plant Bug adult on fruit Yellow, aborting flower buds Droplets of brownish liquid may exude from newly pierced buds Fruit deformation Tarnished Plant Bug damage on fruit damaged seeds Feeding by nymphs Nubbins or deformed fruit Apical seediness Adult feeding CATFACING Feeding in Raspberries Crumbly berry Reduced plant vigour Catfaced berries NOTE: Catfacing can be caused by other factors, producing identical symptoms Monitoring Catfaced berries caused by a range of factors Scout the field perimeter in new fields or entire established fields Survey the field from pre bloom until green fruit stage Tap plants or shake fruit clusters over a nonmetallic pie plate Count the number of nymphs per 100 clusters Economic threshold = 1 nymph per inflorescence (strawberries) 12

13 Careful monitoring of TPB populations Remove weeds (especially leguminous species) Ensure alternate host crops are not planted too close to field / orchards (e.g. alfalfa) Timely application of registered chemicals Saskatoons = Decis application (1st) can be effective RASPBERRY CROWN BORER Raspberry Crown Borer Pennisetia marginata Adult moth resembling yellowjacket wasp Affects all cane fruit Larvae in cane burrow Raspberry Crown Borer pupae Larvae in cane burrow (Photo by A.Antonelli) Raspberry Crown Borer adult Raspberry Crown Borer - adult Larvae girdle new canes while feeding Symptoms may be confused with cane blight Foliage wilts & dies, with fruit remaining attached Damaged canes will break off when pulled (2nd year) Swellings may be apparent at the crown when dug Monitoring Watch for damaged or wilting canes during summer, especially when surrounding plants appear healthy Dig out suspect crowns, looking for holes and sawdust 13

14 Prune out loose canes or canes with galls after harvest Remove & destroy wilting canes during summer Apply registered chemical treatments QUESTIONS??? Rob Spencer, BSA, MSc, P.Ag. Commercial Horticulture Specialist Alberta Ag Info Centre 310 FARM 14