Whole Manual - Michigan State University: Integrated Pest ...

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PHYTOPHTHORA ROOT, CROWN, AND FRUIT ROT DISEASES OF ONIONS PURPLE BLOTCH Phytophthora fruit rot on pickles and watermelon. Pathogen type: fungus (Phytophthora capsici) Disease symptoms: Phytophthora attacks fruits lying on the soil. The fungus causes partial or complete rotting of the fruit. Infected roots and stems are soft, water-soaked and brown. Environmental conditions favoring disease: The fungus prefers moist, humid, warm conditions and is favored by saturated soil conditions. The soilborne fungus is spread readily by splashing water. Control strategies: ■ Crop rotation. ■ Water management. ■ Good drainage and eliminate excess moisture. Purple blotch on onion leaf. Pathogen type: fungus (Alternaria porri) Disease symptoms: Small, white, sunken lesions with purple centers appear on leaves. These spots enlarge to encircle the leaf, resulting in premature senescence. Darkened zones with the characteristic purple color appear on leaf surfaces as the plant matures. Environmental conditions favoring disease: Fungal spores develop in high humidity, rain, or persistent dew with an optimum temperature range of 77 to 85 degrees F. Purple blotch infections are more severe following injury caused by thrips, hail, or wind-blown soil. Control strategies: ■ Plant top-quality seed and disease-free transplants. ■ Dispose of onion culls by incorporating them into the soil immediately after harvest. ■ Practice a three- to four-year crop rotation. ■ Apply fungicides when weather conditions favor disease development. Vegetable Crop <strong>Pest</strong> Management 69 Chapter 7
DOWNY MILDEW SMUT Severe downy mildew infections result in stand decline (top); downy mildew on onion leaves (bottom). Pathogen type: fungus (Peronospora destructor) Disease symptoms: Disease symptoms appear on older leaves as elongated spots. Under humid conditions, the fungus produces purplish spores on the leading edge of the lesion. Eventually, affected leaves turn yellow and collapse. Environmental conditions favoring disease: Fungal spores develop under high humidity, either from rain or persistent dew, at an optimum temperature range of 77 to 85 degrees F. Control strategies: ■ Plant high-quality seed and disease-free transplants. ■ Dispose of onion culls by incorporating them into the soil immediately after harvest. ■ Practice a three- to four-year crop rotation. ■ Apply fungicides when weather conditions favor disease development. Onion smut. Pathogen type: fungus (Urocystis magica) Disease symptoms: Gray streaks appear on leaves, leaf sheaths and bulbs. These streaks are filled with a dark brown, powdery mass of spores. Affected leaves become twisted and deformed and eventually may die. Environmental conditions favoring disease: Cool weather delays plant growth, thereby extending the period an onion is susceptible to onion smut. This soilborne fungus can serve as an infection source for 15 years. Spores are spread whenever soil, water, and plant parts are moved from one place to another. Control strategies: ■ Plant disease-free seed and transplants. ■ Use treated seed. ■ Use an in-furrow fungicide treatment for problem fields. Chapter 7 70 Vegetable Crop <strong>Pest</strong> Management
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Vegetable Crop Pest Management A Gu
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Acknowledgements We would like to e
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General Vegetable Insect Pests . .
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vi Vegetable Crop Pest Management
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accurately written records of field
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Ladybird beetle adults and larvae c
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Phytotoxicity—when a pesticide da
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19. How are tolerance and pesticide
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Always: ■ Select pesticides label
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■ Select the least hazardous pest
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C 2 H A P TER Review Questions Chap
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16 Vegetable Crop Pest Management
Page 25 and 26: Hydraulic Sprayers Water is most of
Page 27 and 28: Nozzles Nozzles are important to co
Page 29 and 30: C 3 H A P TER Review Questions Chap
Page 31 and 32: 24. Granular applicators are design
Page 33 and 34: will not double the flow rate - you
Page 35 and 36: 6. The average output of the nozzle
Page 39 and 40: 32 Vegetable Crop Pest Management
Page 41 and 42: stages. Larvae and adults are often
Page 43 and 44: down into the crown and eventually
Page 45 and 46: INSECT PESTS OF CUCURBITS (CUCUMBER
Page 47 and 48: CABBAGE LOOPER (Trichoplusia ni) Ca
Page 49 and 50: Damage: First-generation European c
Page 51 and 52: ■ Natural enemies such as ground
Page 53 and 54: educed yields. They feed on a wide
Page 55 and 56: C 5 H A P TER Write the answers to
Page 57 and 58: Chapter 5 50 Vegetable Crop Pest Ma
Page 59 and 60: BIENNIAL Biennials complete their g
Page 61 and 62: Advantages of preemergence applicat
Page 63 and 64: 9. Which of the following is true o
Page 65 and 66: BACTERIA Bacteria are very small, m
Page 67 and 68: DISEASE MANAGEMENT Options for dise
Page 69 and 70: Outbreaks occur first as isolated p
Page 71 and 72: FUSARIUM YELLOWS Environmental cond
Page 73 and 74: Pathogen type: fungus (Peronospora
Page 75: MOSAIC VIRUSES POWDERY MILDEW Cucum
Page 79 and 80: humidity. The disease is more likel
Page 81 and 82: BLACK SCURF/STEM CANKER DISEASES OF
Page 83 and 84: ■ Remove or destroy crop residue
Page 87 and 88: 26-29. Match the following cucurbit
Page 89 and 90: PLANT-PARASITIC NEMATODES Plant-par
Page 91 and 92: depending on age. Males are worm-li
Page 93 and 94: Needle nematode feeding can result
Page 95 and 96: 7. Which female nematodes, of those
Page 97 and 98: Chapter 4 Calibration (1) Calibrati
Page 99 and 100: APPENDIX C GLOSSARY ABDOMINAL PROLE
Page 101 and 102: DERMAL TOXICITY—The ability of a
Page 103 and 104: MESOTHORAX—The second segment of
Page 105 and 106: STOMACH POISON—A pesticide that m
Page 107 and 108: Notes 100
Page 109: MICHIGAN STATE U N I V E R S I T Y
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