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

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■ Practice crop rotation to reduce the potential for carryover of the late blight fungus. COMMON SCAB ■ Scout fields regularly for late blight, and as soon as plants show symptoms of infection, begin applications of labeled fungicides according to MSU Extension recommendations. FUSARIUM DRY ROT Potato tuber infected with dry rot. Pathogen type: fungus (Fusarium sambucinum) Disease symptoms: Fusarium dry rot affects potato tubers. Tubers become infected when wounds occur in the skin during harvest and handling. Infected tubers may appear wrinkled or have sunken areas. The internal tissue of the tuber has sharply defined brown, rotten areas. Potatoes that appear normal at harvest can develop disease symptoms after a few weeks. Environmental conditions favoring disease: Fusarium fungi are common soil fungi. Fusarium dry rot does not usually spread from tuber to tuber in storage, but under high humidity, secondary infections of bacterial soft rot may develop. Control strategies: ■ Clean and disinfect all harvest and storage equipment before the beginning of the harvest season. ■ Handle tubers carefully to minimize bruising when harvesting. ■ Do not wash tubers before placing them in storage— this can increase infections and rot. Potato tubers infected with common scab. Pathogen type: bacteria-like organism (Streptomyces scabies) Disease symptoms: Common scab affects potato tubers. Tiny, dark spots develop on the tuber and rapidly expand, producing brown areas with a cork-like texture—scabs. The scabs may be raised, pitted, or shallow, depending on environmental conditions, the strain of bacterium, and the potato variety. Environmental conditions favoring disease: Scab development is favored by dry soil conditions and alkaline soils. The disease organism enters the plant through wounds or natural openings such as stomata or lenticels. It is spread by infected seed potatoes, wind and soil. Control strategies: ■ Use scab-free certified seed. ■ Maintain a low soil pH and healthy soil. ■ Maintain adequate soil moisture during tuber initiation to minimize scab development. Vegetable Crop <strong>Pest</strong> Management 73 Chapter 7
BLACK SCURF/STEM CANKER DISEASES OF SNAP BEANS FUSARIUM ROOT ROT Fusarium root rot in snap beans. Pathogen type: fungus (Fusarium solani f. sp. phaseoli) Disease symptoms: Two to three weeks after planting, reddish brown streaks appear on the stem just below the soil surface. The lesions may extend upward to the soil surface and become brown with age. Severely infected roots die. Plants appear stunted with yellow leaves, but the fungal infection seldom kills the entire plant. Rhizoctonia solani causes tuber and stem damage in potatoes. Pathogen type: fungus (Rhizoctonia solani) Disease symptoms: This pathogen is both seed- and soilborne. On tubers, irregularly shaped, black, canker-like masses appear—black scurf. The pathogen causes brown to black lesions on belowground stems of immature plants. Eventually, these lesions sink into the stem surface, causing cankers that can girdle and kill stolons or stems. This results in pruning and loss of tuber development sites. Environmental conditions favoring disease: Disease development is enhanced during cool, wet weather and in cold, wet soil. Environmental conditions favoring disease: Early planting in cool, moist soil favors the disease. Any conditions reducing root growth increase the likelihood of infection with Fusarium root rot. The pathogen can survive for years in the soil in the absence of beans. Control strategies: ■ Avoid plant stress. The disease causes little damage to healthy plants. A three-year crop rotation out of beans reduces the chance of a Fusarium infection. WHITE MOLD Control strategies: ■ Practice crop rotation with non-host crops. ■ Encourage rapid plant development of sprouts to reduce the disease severity. ■ Remove plant residue to allow soil to dry out and warm up in the early spring. ■ Plant disease-free seed. Seed treatment effectively controls the seed-borne pathogen. White mold kills branches and stems, giving them a white appearance. Chapter 7 74 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
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Hydraulic Sprayers Water is most of
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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 and 76: MOSAIC VIRUSES POWDERY MILDEW Cucum
Page 77 and 78: DOWNY MILDEW SMUT Severe downy mild
Page 79: humidity. The disease is more likel
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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