Which two diseases are concerns for apples in Wisconsin?

Which two diseases are concerns for apples in Wisconsin?

• A. Powdery mildew and rust
• B. Late blight and downy mildew
• C. Botrytis and brown rot
• D. Apple scab and Fire blight

Answer: (D)

In Wisconsin, humid springs and cool, wet conditions create ongoing disease pressure on apples, so two diseases stand out as common and troublesome for many home orchards and commercial trees: apple scab and fire blight. Apple scab is caused by a fungus, Venturia inaequalis, and flourishes when springs are damp and mild. It greets the leaves first with olive‑green to brown spots, which can merge and cause leaf distortion and premature leaf drop. On fruit, it leaves dark, scabby lesions that reduce marketable quality. Because it overwinters in fallen leaves and multiply quickly when spring weather is wet, it’s a routine concern in this region. Management focuses on sanitation (removing and destroying infected leaves and fruit), selecting resistant cultivars when possible, and timely fungicide applications at key growth stages. Fire blight is a bacterial disease, Erwinia amylovora, that thrives in warm, wet springs. It causes blossoms to appear scorched or water-soaked, shoots to wilt and die back, and cankers to form on branches. It can spread rapidly and, in severe cases, threaten tree vigor and longevity. Management emphasizes pruning out infected wood during dry weather, orchard hygiene to remove sources of bacteria, and protective sprays on susceptible varieties. The other options involve diseases that either are less consistently problematic for apples in Wisconsin or are more strongly associated with other crops or less severe in this region, so they are not the two most typical concerns here.

In Wisconsin, humid springs and cool, wet conditions create ongoing disease pressure on apples, so two diseases stand out as common and troublesome for many home orchards and commercial trees: apple scab and fire blight.

Apple scab is caused by a fungus, Venturia inaequalis, and flourishes when springs are damp and mild. It greets the leaves first with olive‑green to brown spots, which can merge and cause leaf distortion and premature leaf drop. On fruit, it leaves dark, scabby lesions that reduce marketable quality. Because it overwinters in fallen leaves and multiply quickly when spring weather is wet, it’s a routine concern in this region. Management focuses on sanitation (removing and destroying infected leaves and fruit), selecting resistant cultivars when possible, and timely fungicide applications at key growth stages.

Fire blight is a bacterial disease, Erwinia amylovora, that thrives in warm, wet springs. It causes blossoms to appear scorched or water-soaked, shoots to wilt and die back, and cankers to form on branches. It can spread rapidly and, in severe cases, threaten tree vigor and longevity. Management emphasizes pruning out infected wood during dry weather, orchard hygiene to remove sources of bacteria, and protective sprays on susceptible varieties.

The other options involve diseases that either are less consistently problematic for apples in Wisconsin or are more strongly associated with other crops or less severe in this region, so they are not the two most typical concerns here.