1	Insect control on vegetables Jeffrey Wyman Department of Entomology
2	Vegetable Production in Wisconsin Important production state nationally Good crop climate also limits pests Production linked historically to canning industry Recent increase in fresh market
3
4	Insect Management on Vegetables The problem: Many Insects on Many Crops Some perspective on insects: Why is it difficult to manage insects? Lots of insect species on the planet Over 1 million animal species ¾ are arthropods Remember: only a few are actually pests Each species has lots of individuals Short life cycles High numbers of individuals Combination = HIGH REPRODUCTIVE CAPABILITY
5	Insect Reproductive Potential Example: Fruit flies 2 week life cycle = 25 generations per year 100 eggs per female If 1 pair mate and all offspring survive for 1 year = 10⁴¹ flies!! If packed 1000 flies/cubic inch = ball of flies 96 million miles in diameter = ½ the distance to the sun! So,why have the insects not taken over?
6	Factors that regulate insect populations Physical Factors Environment Temperature, rainfall Pesticides Biological Factors Influence increases at higher populations Competition Food availability Parasites, predators disease
7	Insect Management è The 6-step Process Identify the “key” pests Look closely at : Biology Ecology Behavior Impact on crop Identify weak links Develop management strategies to exploit weaknesses Tailor IPM to individual needs Fit sporadic pests into program
8	Insect Management Trends on Vegetables 1950’s to 1980’s
9	Insect Management Trends on Vegetables 1980’s to 1990’s = Problems
10	Insect Management Trends on Vegetables
11	Insect Management Trends on Vegetables Use 3 crops, potatoes, cole crops and snap beans, to illustrate major trends in IPM for commercial crops and explore linkages to smaller scale IPM Examine insect pests, damage and approaches to control in a range of other commonly grown crops Sweet corn, peppers, tomatoes Cucurbits, carrots
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62	"Excellent example of potential..." Excellent example of potential for biological control (Mahr et. al. NCR Regional pub. 471) History of problem Direct damage to marketable product by key pests Worms on heads Maggots on roots Multiple insecticide applications used Resistance developed as threat to production Solution IPM implementation based on biological control of key pests Pesticides switched to specific, ‘soft’ materials to preserve natural control
63	Key Pests of Cole Crops Complex of 3 lepidopteran species All feed on marketed crop Need to identify species but can treat as a complex
64
65	Diamondback moth Occurrence Does not overwinter in Wisconsin Blown in on wind or imported on plants 4-8 generations per year Damage ‘Window pane’ feeding, may also deform heads 1^st instar mine in leaf Damage usually early-mid season (June/July) Resistance to many insecticides Major problem worldwide
66	Imported Cabbage Worm life cycle
67	Imported Cabbage Worm Occurrence Overwinters as pupae in Wisconsin 3 generations per year, 1^st on weeds Damage Usually most damaging species in Wisconsin Large holes in leaves and heads Often extensive frass Peak damage mid-season (June/July)
68	Cabbage Looper life cycle
69	Cabbage Looper Occurrence Does not overwinter, adults blow in (June/July) 2 generations per year, persisting in late season Damage Damage usually late season Extensive leaf holes and head damage
70	Managing the Lep. Complex Cultural Use clean transplants Biological Good complex of parasites Diamondback moth: 70-90% parasitized Imported Cabbage worm: 30-60% Cabbage looper: 10-30% Multiple species
71	Managing the Lep. Complex Chemical Pest Specific Bacillus thuringiensis (Kurstaki; Btk, or Azaiwi; Bta) Many materials registered e.g. Dipel, Thuricide, Biobit, Cutlass, etc. Short persistence è timing critical Stomach poison è coverage important Weak on looper Broad Spectrum Pyrethroids Multiple applications Resistance can be a problem Eliminate biological controls
72	Key Pest of Root Crops
73	Cabbage Maggot Life Cycle Occurrence Overwinters in soil as pupa Adults emerge in spring 3 flight peaks First peak is most serious and occurs at 300 heat units or when lilacs bloom (May) Damage Larvae tunnel on root surface May be secondary rot Major importance on root crops Causes wilting, death on head crops
74	Cabbage Maggot Management Cultural Rotate crop away from overwintering site (1/4-1/2 mile) Prevent egg laying with barrier, row cover Predict egg laying with heat units (300 HU with 43˚F base) Plant early or late to avoid eggs Biological Some egg predation by beetles Chemical None currently available Diazinon withdrawn
75	Sporadic Pests of Cole Crops
76	Flea Beetle Management Cultural Exclude adults with row cover Attract adults to alternate trap crop (Indian mustard) Avoid early planting Biological No effective controls Chemical Spray to control adults Carbaryl, pyrethroids DO NOT disrupt biological controls for lepidoptera
77	Sporadic Pests of Cole Crops
78	Cabbage Aphid Management Cultural None available except exclusion Biological Parasites and predators are effective Chemical No effective controls Insecticidal soap may suppress colonies
79	Cabbage Aphid Natural Controls
80	Putting together a biologically-based management program for cole crops 3 requirements Existing or obtainable natural enemies for key pests Pest specific insecticides to conserve natural enemy control Non-disruptive controls for sporadic pests
81	Natural Occurring Parasitization of Lepidoptera Diamondback moth 70-90% Imported cabbage worm 30-60% Cabbage looper 10-30%
82	Parasites of Diamondback Moth Diadegma insulare is primary parasite Stings mid-stage larvae with single egg Kills pupa Replaces host pupa in case
83	Parasites of Imported Cabbage Worm Cotesia glomerata Stings small larvae and inserts several eggs Larvae develops until parasites pupate 20-50 parasites emerge from late instar Pteromalus puparum Stings pupa Eggs divide Parasite larva kill host pupa Up to 200 parasites emerge
84	Parasites of Cabbage Looper Trichogramma Tiny wasp lays egg in host egg Parasite kills egg and emerges Copidosoma floridanum Tiny wasp lays egg in host egg Host continues to develop Parasite divides and kills late instar larvae 200-400 parasites emerge Voria ruralis Large fly stings small host larvae Larva and parasites develop Large larva killed and 2-3 parasites emerge
85	Pest Specific Insecticides for Key Pests Control lepidoptera at thresholds when needed Conserve beneficial organisms
86	Non-disruptive controls for sporadic pests Cabbage maggot Timing or avoidance Row cover Rotation of crop Aphids Predators Parasites Flea beetles Trap crops (mustard)
87	Cole Crop insect control - Summary Manage key lepidopteran pest complex with combinations of: Biological control with parasites Soft biological insecticides Manage other pest with tactics which will not interfere with biological control Cabbage maggot è cultural/physical Aphids è predators Flea beetle è rowcover
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105	Sporadic pests of snap bean – tarnished plant bug
106	Tarnished Plant Bug - Control Cultural Avoid planting next to alfalfa Control weeds and edges Biological None Chemical Rarely needed Threshold: 2/sweep in bud stage Pyrethroids effective
107	Sporadic pests of snap bean – Soybean aphid
108	Soybean Aphid Management Cultural Plant early to avoid infestation Biological Predators are not effective – Asian ladybeetle only on soybeans Chemical Not required for fresh market
109	Sporadic pests of snap bean – Common stalk borer
110	Common Stalk Borer Management Cultural Mow grass/weed edges Can attack wide range of plants Biological None effective Chemical Rarely needed Pyrethroids effective as edge treatments
111	Sporadic pests of snap bean – Bean Leaf Beetle
112	Bean Leaf Beetle Management Cultural Plant late to avoid 1^st generation adults Row cover for 2^nd generation Avoid planting adjacent to soybeans Biological None are effective Chemical Treat if defoliation is over 10% or if pods are present Carbaryl or pyrethroids are effective
113	Sporadic pests of snap bean – Mexican Bean Beetle
114	Mexican Bean Beetle Management Cultural Avoid planting beans where beetle is established Clean up overwintering protection Plant late Biological None are effective Chemical Treat if defoliation is over 10% or if pods are present Carbaryl or pyrethroids are effective
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131	Pepper Insect Control
132	European corn borer
133	European Corn Borer control Cultural Plant early to avoid 2^nd generation Do not plant adjacent to sweet corn Discard infested fruit Biological None effective Chemical Only use for 2^nd generation protection Only use if adult pressure is high Pyrethroids are effective Pymethrin, cyfluthrin
134	Green Peach Aphid
135	Green peach aphid control Cultural Early planting Biological Effective Predators and parasites Chemical Avoid use if possible to preserve natural control Only esfenvalerate, acephate are effective Soapy water may reduce
136	Tomato Insect Control
137	Insect Pests of Tomato Tomato fruitworm (corn earworm) Tomato hornworm Aphids Cutworms Leafminer Whitefly
138	Tomato Fruitworm (corn earworm, cotton bollworm)
139	Tomato fruitworm
140	Tomato fruitworm control Cultural Plant early to avoid Discard infested fruit Biological Effective parasites But will not prevent damage Chemical Rarely necessary Disrupts natural control of other pest (leaf miner, aphid)
141	Tomato Hornworm Life Cycle
142	Tomato hornworm
143	Tomato hornworm control Cultural Remove larvae from plants and squash! Biological Very effective usually Both predators (eggs) and parasites (larvae) Chemical Avoid if possible to preserve natural control Bt is effective
144	Tomato insect pests - Cutworms
145	Cutworm control Cultural Protect plant with barrier, row cover Control weeds/debris Biological Not effective Chemical Not effective
146	Tomato leafminer
147	Aphids – Potato aphid
148	Aphid control Cultural None effective Biological Very effective Predators and parasites Fungal diseases Chemical None are effective Insecticidal soap
149	Whitefly
150	Whitefly control Cultural Only use clean transplants Biological None effective Chemical None are effective
151	Insect Control on Carrots 4-5000 Acres in Wisconsin Processing and fresh Cut/peel carrots not yet produced here Few serious insect problems
152	Aster Leafhopper
153	Aster Yellows
154
155
156
157	Cucurbit Insect Control
158	Insect Pests of Cucurbits
159	Seed corn maggot life cycle
160
161
162	Cucumber beetles
163	Cucumber beetle control Cultural Plant late Eliminate weeds, weedy edges Row cover early Biological None effective Chemical Use if wilt is a problem Avoid flowering to protect bees Pyrethroids are effective
164	Squash vine borer life cycle
165	Squash vine borer
166	Squash vine borer control Cultural Protect base of plants (row cover) Physically kill larvae Biological None effective Chemical Pyrethroids,carbaryl
167	Cucurbit – sporadic insect pests
168	Sporadic pests – squash bug
169	Sporadic pests –melon aphid
170	Melon aphid control Cultural Reflective mulch to repel aphids Black plastic, white plastic, foil Biological Effective predators Chemical Few affective Insecticidal soap
171
172