| | Insect Pest Occurrence - Fruit | Insect Pest Occurrence - Vegetables | Seasonal Disease Occurrence - Fruit | Seasonal Disease Occurrence - Vegetables
There are a number of insect pests and plant diseases that may attack fruit and vegetable crops each season. Not all of them occur every year and the severity will also vary, depending on a number of factors. Understanding when an insect pest is at a vulnerable stage of development or when a disease is more likely to occur will allow management practices to be most effective, and will reduce ineffective and wasteful applications. Preventative and protective practices can be implemented, minimizing crop losses.
The following charts and tables represent general ranges of when pests (and their respective stages) may occur. It is important to recognize the depending on the region, the earliest, latest and average dates that stages occur may shift. In general, these dates are reasonable estimates for pests on the Canadian Prairies.
Seasonal Insect Pest Occurrence - Fruit Crops
For a PDF version of the following table - click here
For a PDF version of a graphic representation of the following table - click here
Pest Name | Host Crops | EGGS | LARVAE | NYMPHS | PUPAE | ADULTS | ALL STAGES |
Aphids | Many | | | | | | Apr to Sept |
Apple Curculio | Saskatoon berry, chokecherry, crabapple, hawthorn & pear | | | June-July | | mid-Apr to end-May / mid-July to end-Sept | |
Apple Maggot | Apple, crabapple, sweet/tart cherry, etc. | July | mid-July to Sept | | Sept (overwinter) | late-June-early-July to end-Oct | |
Brown Marmorated Stink Bug | Wide range – over 300 different hosts – berries, grapes, stone & pome fruit | Early June until late July or early August |  | 5 stages – throughout summer | | Emerge May to June; stick around throughout season | Single generation per season |
Note – most stages likely occur elsewhere than Alberta, at present – typically arrive as hitchhikers |
Cherry Shoot Borer | Chokecherry, Saskatoon berry, hawthorn | mid-Apr to mid-May | mid-May to end-June | | | end-May to start-Aug | |
Chokecherry Fruit Gall Midge | Chokecherry, Saskatoon berry | | mid-May to mid-July | | Apr to mid-May | May to end-June | |
Currant Fruit Fly | Currants and gooseberries | late-May to early-July | early-June to July | | Aug to overwinter | mid-May-early-June to late-June | |
Cyclamen Mite | Strawberry | | | | | | ALL
(Mult gen) |
Hawthorn Lace Bug | Saskatoon berry & other Rose family plants | May; mid-July to mid-Aug | | mid-May to late-June / late-July to mid-Sept | | Apr to mid-May / July to mid-Aug / mid-Sept+ | |
Leafhoppers | chokecherry, Saskatoon berry, raspberry, strawberry | | | start-June to mid-June | | May / mid-June to end-Sept | |
McDaniel’s Spider Mite | Saskatoon berry | | | | | | ALL
(Mult gen) |
Meadow Spittle Bugs | Strawberry, other non-fruit species | April to mid-May | | late-May to mid-July | | mid-late-June to mid-Aug | |
Pear Slug | Saskatoon berry, pin cherry, cotoneaster, hawthorn, chokecherry | | late-June to end-Aug | | Apr to early-June / mid-Aug to end-Sept | early-June to mid-July | |
Raspberry Crown Borer (2-YR LIFECYCLE) | Caneberries | Sept to Oct | Sept to Oct | | | early-Aug to end-Sept | All stages present in any one year |
2ND YEAR | | | Apr to Sept | | July | | |
Raspberry Sawfly | Caneberries, gooseberry, etc. | | June to early July (above ground); Late June to end-Sept (in soil) | | April | | |
Root weevils | Strawberry, raspberry, range of other crops | | April; Mid-July to end-Sept | | May to end-June | late-June to end-Aug | |
Saskatoon Bud Moth | Saskatoon berry | | early-May to late-Aug | | early-mid-April to early May; Sept | April to early-mid-May | |
Saskatoon / Chokecherry Sawfly | Saskatoon berry, chokecherry | | early-June to early-Aug | | April to mid-May | Mid-May to late June | |
Slugs | Strawberry + range of hosts | early-May to early-mid-July | mid-May to end-July | | | late-June to end-Sept | |
Spotted Wing Drosophila | Strawberry, caneberry, bushberries (blueberry, Saskatoon berry, etc.) | June to Sept | late-June to Sept | | July to Sept | June to Sept (in some areas) | June to Sept |
Strawberry Bud/Clipper Weevil | Strawberry; caneberries, other | | mid-May to late-June | | | Apr to late-May / late-June to end-Sept | |
|
Tarnished Plant Bug / Lygus Bug | Strawberry | | | early-May to late-Aug | | May; late-June to end-Sept | |
Raspberry | | | May to Aug | | April to late-May; late-June to end-Sept | |
Thrips | Strawberry, caneberry, tree fruit, etc. | Overwinter in USA | | | | | mid-May to mid-Aug |
Two-Spotted Spider Mites | Strawberry, raspberry, etc. | | | | | | ALL
(Mult gen) |
Ugly Nest Caterpillar | Chokecherry, pin cherry, etc. | April | May to Aug | | | late-June to end-Sept | |
Woolly Elm Aphid / Wooly Apple Aphid | Saskatoon berry, elm (alternate host) | April (on elm) | | | | late-Apr to Sept (on Saskatoon); Aug to Sept (migrates to Elm) | May to Sept (some winged migratory stages) |
* Note – occurrence timelines are estimates only and can vary according to seasonal conditions and other factors – use a general guideline
** See below for graphic representation of seasonal pest occurrence
*** Adapted and expanded from MAFRI Fruit Crop Insect Guide
Seasonal Insect Pest Occurrence - Vegetables
For a PDF version of the following table - click here
For a PDF version of a graphic representation of the following table - click here
Pest Name | Host Crops | Eggs | Larvae | Nymphs | Pupae | Adults | All Stages |
Aphids | Many vegetable crops | | | | | May to Sept - Multiple generations | |
Aster Leafhopper | Many vegetable crops | early Spring or other crops in other regions; Multiple generations | | Multiple generations per season - late July to end-Sept | | Multiple generations - 1st generations late-May to early-June; June-Sept | May have 1-4 generations per season |
Beet Webworm | Many vegetable crops | mid-May to July; mid-July to Sept | late-June to early July; late-Aug to Sept (overwinter) | | late-May; Sept to overwinter | mid-May to July; mid-July to Sept | |
Brown Marmorated Stink Bug | Wide range – over 300 different hosts – peppers, tomatoes, corn, etc. | Early June until late July or early August | | 5 stages – throughout summer | | Emerge May to June; stick around throughout season | Single generation per season |
Note – most stages likely occur elsewhere than Alberta, at present – typically arrive as hitchhikers |
Cabbage Looper | Cole crops + other cruciferous crops | July | mid-July onward | | late-July to Aug | June-Sept | One generation per year |
Cabbage Maggots | Cole crops + other cruciferous crops | mid-May to June; mid-July to Aug; late-Aug to Sept | June to July; Aug to Sept | | mid-July; late Sept overwinter | May to Aug-Sept | 1-3 generations per season |
Colorado Potato Beetle | Plants in Solanaceous family | late-May to July | early-June to Aug | | July to Aug | late-May-early-June to Sept; Overwinter as adult | All season; typically 1 complete generation per season |
Crucifer Flea Beetles | Cruciferous crops | mid-May to June | late-May to July | | | mid-May to June; late-July to overwinter | Typically 1 generation per season |
Cutworms | Range of host crops | Aug to mid-Sept | late-Apr to June; late-Sept to overwinter; most overwinter as larvae | | May to early June; some overwinter as pupae | June-July (hibernate); late-Aug to Sept | Timing and duration of stages depends on the species |
Diamondback moth | Cole crops + other cruciferous crops | mid-May to Sept | mid-May to Sept | | June to Sept | early-May to Sept | Multiple generations per season |
European Corn Borer | Corn, snap bean, potato, eggplant, pepper | late-July | late-July to overwinter pupation | | May to June | late-June to early Aug | 1 generation on Prairies |
Imported Cabbageworm | Cole crops + other cruciferous crops | late-May to Sept | June to Sept | | late-June to Sept; overwinter as pupae elsewhere | mid-May to Sept | 2-3 generations per year |
Onion Maggots | Bulb vegetables | June to early-July | June to early-Aug | | Overwinter; late-July | late-May to June; repeats later in season | May be more than 1 generation per season |
Pea Leaf Weevil | Peas | May to June | June to July | | July | May to June; late-July to Aug (then overwinter) | 1 complete generation per season |
Swede Midge | Cole crops | mid-May to Sept | late-May to Sept | | June to Sept | mid-May-early-June to Sept (multiple generations) | Multiple generations per season (in some areas) |
Tarnished Plant Bug / Lygus Bug | Many vegetable crops | May to July | | end-May to Aug | | late-Apr to Sept; overwinter | Multiple generations per season |
Tuber Flea Beetles | Potatoes | mid-May to June | June to July | | | mid-May to June; late-July to overwinter | Typically 1 generation per season |
Two-Spotted Spider Mites | Bean, cucurbits, eggplant | | | April to late-Sept | | Overwinter to Sept | Multiple generations per season |
Wireworms | Range of host crops | May | all season - several years | | | May | Life cycle spans several years |
* Note – occurrence timelines are estimates only and can vary according to seasonal conditions and other factors – use a general guideline
** See below for graphic representation of seasonal pest occurrence
*** Prepared with contributions from Dr. Ken Fry, Olds College
Seasonal Disease Occurrence - Fruit
For a PDF version of the following table - click here
Pest Name | Host Crops | Causal Organism | Mode of Carryover | Mode of Transfer | Seedlings | Roots | Branches / Canes | Foliage | Flowers | Fruit |
Entomosporium Leaf & Berry Spot | Saskatoon berry | Entomosporium mespili | Unknown - lesions on infected plant parts; in debris | Spores | - | - | Y - insignif | Y | Y | Y |
Mummyberry | Saskatoon berry | Monilinia amelanchiaris | mummified fruit | spores | - | - | - | sometime | Y | Y |
Saskatoon berry / Juniper Rust | Saskatoon berry (juniper = secondary host) | Gymnosporangium mespili | spore stages on alternate host (juniper) | spores from junipers; spores on saskatoon berry | - | - | - | Y | - | Y |
Blackleaf / Witches’ Broom | Saskatoon berry | Apiosporina collinsii | Infected plant material (wild, etc) | Spores | - | - | Y | Y | - | indirect-Y |
Fireblight | All plants within Rosaceae (saskatoon berry, apple, etc.), caneberries | Erwinia amylovora | branch cankers | insects, rain / water splash, Physical transfer (pruning) | - | - | Y | Y | Y | N - indirect |
Botrytis grey mold | Strawberry, raspberry, etc. | Botrytis cinerea | infected plant material; sclerotia; spores | spores | Y | - | Y | Y | Y | Y |
Powdery Mildew | Strawberry, Saskatoon berry, raspberry, black currants | Spaerotheca macularis f.sp fragariae; Podosphaera clandestina; | cleistothecia (sexual spores) | windblown spores | - | - | Y | Y | - | Y |
Pythium root rots | Strawberry, raspberry, etc. | Pythium spp. | soil borne mycelium, sporangia, oospores | germinating oospores | Y | Y | - | Y - seedlings - indirect | - | - |
Cane Blight | Caneberries | Leptosphaeria coniothyrium | lesions on infected canes | spores | - | - | Y | Y | Y-indirect | N-indirect |
Spur Blight | Caneberries | Didymella applanta | lesions on infected canes | spores | - | - | Y | Y | Y-indirect | N-indirect |
Common Leaf Spot | Strawberry | Mycosporaella fragariae | infected plant material (in field, propagative material) | spores - rain or mechanical transfer | - | - | - | Y | - | Y- black seed |
Black Knot | Prunus spp. | Apiosporina morbosa | Galls | Spores produced on infected wood | - | - | Y | indirect | - | - |
Brown Rot / Cherry Blossom Blight | Prunus spp. | Monilinia spp. | mummified fruit; infected plant parts | spores disseminated by wind, rain, insects | - | - | Y - twigs | - | Y | Y |
Cytospora canker | Saskatoon berry; other crops (dif spp.) | Cytospora leucostoma | cankers in infected tissues | via wounds | - | - | Y | Y-indirect | - | - |
Root rots | Raspberry, etc. | Fusarium, Rhizoctonia, etc | soil borne | soil to plant | Y | Y | - | N- indirect | - | - |
Black Root Rot | Strawberry | Rhizoctonia, Pythium, etc. | soil borne; infected plant stock | soil to plant | Y | Y | - | N- indirect | - | - |
Verticillium Wilt | Strawberry, raspberry, other fruit | Verticillium albo-atrum; V. dahliae | microsclerotia or mycelium on crop debris or in soil | spores or spores in soil | Y | Y | Y - indirect | Y - indirect | - | - |
Pest Name | Timing | Control | Storage |
Entomosporium Leaf & Berry Spot | Foliar infection can occur throughout summer; Fruit infection from flowering to harvest | Protective sprays | N |
Mummyberry | May to June (during bloom) | Remove inoculum; protective sprays | N |
Saskatoon berry / Juniper Rust | June to August | Apply protective sprays; control on junipers | N |
Blackleaf / Witches’ Broom | Infection of new growth in spring | Pruning in dormant season | N |
Fireblight | Throughout growing season once active growth commences | Prune out diseased material | N |
Botrytis grey mold | Can occur at any point in growing season | Remove debris; Protective sprays | Y |
Powdery Mildew | Spring or fall | Ensure air movement; fungicide application | N |
Pythium root rots | early season or whenever young plants are present | good drainage; seed treatments | N |
Cane Blight | mid-late season; depends on environmental conditions | Protective sprays | N |
Spur Blight | mid-late season; depends on environmental conditions | Protective sprays | N |
Common Leaf Spot | Early season or late summer | Clean plants; adequate air flow; protective sprays | N |
Black Knot | infection occurs in early spring | Pruning in dormant season | N |
Brown Rot / Cherry Blossom Blight | During bloom & fruiting stages | Remove inoculum; protective sprays | N |
Cytospora canker | Can occur at any point in growing season | Remove infected tissues | N |
Root rots | Depends on the weather | Clean plants; good drainage | N |
Black Root Rot | Depends on the weather | Clean plants; good drainage | N |
Verticillium Wilt | Dependant on weather & crop stage | seed, soil treatment; clean plants | N |
Seasonal Disease Occurrence - Vegetables
For a PDF version of the following table - click here
Pest Name | Host Crops | Causal Organism | Mode of Carryover | Mode of Transfer | Seedlings | Roots | Stems / Branches | Foliage | Flowers | Fruit | Seeds | Tubers |
Aster Yellows | Wide range | mycoplasma-like organism | Infected host plants | Aster Leafhopper | Y | Y | Y | Y | Y | Y | - | - |
Bacterial Soft Rot | Wide range | Erwinia carotovora subsp carotovora or atroseptica | soil borne | via wounds/weak points; in storage, wash water; | N | Y | Y | Y | N | Y | N | Y |
Botrytis | Wide range | Botrytis cinerea | spores; mycelium; sclerotia | spores; mycelium | Y | - | - | Y | Y | Y | - | - |
Clubroot | Cruciferous crops | Plasmodiophora brassicae | resting spore in soil | germinating resting spores; transfer of spores in water, soil, etc. | Y | Y | - | indirect - stunting | - | - | - | - |
Common Blight | Beans | Xanthomonas campestris pv phaseoli | infected seed; contaminated soil | rain splash; physical contact; insects, etc | - | - | - | Y | - | Y | Y | - |
Common Scab | Potato, beets, carrots, turnips, rutabaga, radish | Streptomyces scabies | Soil borne; infected seed | soil to tuber (via lenticels) | - | - | - | - | - | - | - | Y |
Downy Mildew | Beets, spinach, cole crops, radish, rutabaga/turnip, lettuce, rhubarb, onion, garlic, peas | Perenospora spp. (depends on host crop) | oospores in soil, debris, plant parts | spores - water splash, wind | Y | Y - crown infect | - | Y | - | - | - | - |
Early Blight | Potato, tomato, pepper, eggplant | Alternaria solani | Soil, crop residues, alternate hosts | spores - soil to tissue transfer; rain splash | - | - | - | Y | - | Y | - | Y |
Fusarium dry rot | Potato | Fusarium sambucinum, F. solani, F. coeruleum, F. avenaceum | contaminated soil or infected seed | wounds | - | - | - | - | - | - | - | Y |
Halo Blight | Beans | Pseudomonas syringae pv phaseolicola | infected seed; contaminated soil | rain splash; physical contact; insects, etc | - | - | - | Y | - | Y | Y | - |
Late Blight | Potato, tomato, pepper, eggplant | Phytophthora infestans | On living tissues (tubers, etc) | sporangia; rain splash; on storm fronts | Y | - | - | Y | - | Y | - | Y |
Neck rots | Bulb vegetables | Botrytis aclada, B. byssoidea, B. squamosa | Sclerotia in bulbs, debris, cull piles, volunteers, soil | spores via air; wounding at harvest | - | - | - | Y - bulbs | - | - | - | - |
Pink Rot | Potato | Phytophthora erythroseptica | soil borne | infection of stolons, eyes, lenticels; via wounds at harvest | - | - | - | - | - | - | - | Y |
Powdery Mildew | cruciferous crops, peas, lettuce, rhubarb, cucurbits | Erysiphe polygoni; E. cichoracearum | cleistothecia (sexual spores) | windblown spores | - | - | Y | Y | - | Y | - | - |
Pythium root rots | Wide range | Pythium spp. | soil borne mycelium, sporangia, oospores | germinating oospores | Y | Y | - | Y - seedling - indirect | - | - | - | - |
Rhizoctonia / Black Scurf | Potato | Rhizoctonia solani | sclerotia in soil or on seed tubers | soil to plant parts | Y | Y | Y | - | - | - | - | Y |
Sclerotinia rot | Carrots, lettuce, beans, cole crops, potatoes, peas, cucurbits, solanaceous crops, etc. | Sclerotinia sclerotiorum | sclerotia in soil or on plant debris | spores; germinating sclerotia | Y | Y | Y | Y | - | - | - | - |
Slippery Skin | Bulb vegetables | Pseudomonas gladioli pv. allicola | soil borne | rain splash of soil; via wounds | - | - | Y - neck area | Y - bulbs | - | - | - | - |
Silver Scurf | Potato | Helminthosporium solani | in soil or in debris in soil | soil to tuber | - | - | - | - | - | - | - | Y |
Verticillium Wilt | Potato, tomato, pepper, eggplant, cucurbit crops | Verticillium albo-atrum; V. dahliae | microsclerotia or mycelium on crop debris or in soil | spores or spores in soil | Y | Y | Y - indirect | Y - indirect | - | - | - | - |
Pest Name | Storage | Timing | Control |
Aster Yellows | N | June to Sept | Control insect vector |
Bacterial Soft Rot | Y – spreads | Typically post-harvest | crop rotation; careful post-harvest handling; |
Botrytis | Y | any point in the growing season with suitable conditions | Adequate fertilizer; protective sprays; timely harvests |
Clubroot | N | any point in summer - typically in early summer | Rigorous sanitation; Long rotations; Avoid contamination |
Common Blight | N | any point in summer | Use clean seed; bury residues |
Common Scab | Visible; does not spread or increase | Infection occurs during 5 weeks (flowering onward) | Clean seed; seed treatments; even watering; variety selection |
Downy Mildew | N | Dependant on weather | Crop rotation; bury debris; protective sprays |
Early Blight | Y - does not spread | mid-late summer | Crop rotation; protective sprays; avoid plant stress |
Fusarium dry rot | Y; does not spread | Wounding during harvest or post-harvest | Careful handling during harvest & post-harvest |
Halo Blight | N | any point in summer | Use clean seed; bury residues |
Late Blight | Y | any point in summer - depends on point of infection | Monitoring/early detection; protective sprays; clean seed potatoes |
Neck rots | Y - increases in severity & as symptomless bulbs develop | mid-late summer to harvest | Reduce inoculum; avoid wounding; cure after harvest |
Pink Rot | Y - spreads in storage | late summer; at harvest | Crop rotation; Cull after harvest; fungicides applied around planting or tuber set |
Powdery Mildew | N | Spring or fall | Good airflow; crop rotation; remove inocululm |
Pythium root rots | N | early season or whenever young plants are present | good drainage; seed treatments |
Rhizoctonia / Black Scurf | Y - visible - doesn't increase or spread | early spring or late season | seed treatments; good growing conditions |
Sclerotinia rot | Y | any point in summer | Remove inoculum; protective sprays; post-harvest management |
Slippery Skin | Y - doesn't spread | mid-late summer | careful irrigation; proper post-harvest handling |
Silver Scurf | Y | Before or at harvest | Seed treatments; quick harvest; cold storage |
Verticillium Wilt | N | Dependant on weather & crop stage | seed, soil treatment; clean plants |
Note – occurrence timelines and disease attack points are estimates only and can vary according to seasonal conditions and many other factors – use a general guideline
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