Vegetable and Fruit Crops Pathology

I. Orange Rust of Brambles

AOrange rust is the most important of several rust diseases that attack brambles. All varieties of black and purple raspberries and most varieties of erect blackberries and trailing blackberries are susceptible to orange rust. In the past two year severe infection of orange rust has been observed in commercial orchards in Illinois.

Orange rust is easily identified shortly after new growth appears in the spring. Newly forming shoots are weak and spindly. Leaves on such canes are stunted and misshapen and pale green to yellowish. Within a few weeks, the lower surface of infected leaves are covered with blister-like pustules that are initially waxy but turn powdery and bright orange. These "rusted" leaves wither and drop by early summer.

Young, apparently healthy canes, with normal leaves can be found toward the end of June. Unfortunately, diseased plants are systemically infected, and the fungus is present in the roots, canes, and leaves. Infected canes will be bushy and spindly, and will bear little or no fruit in the following season.

To control orange rust:plant only certified, disease-free planting stock from a reputable nursery; before setting out new plants, remove and burn all wild brambles and any cultivated plants that are rust infected, including the roots; when the disease first appears in early spring, dig up and burn infected plants before the pustules break open and discharge spores; improve air circulation by thinning out healthy canes in the rows and keeping the planting free of weeds; plant resistant cultivars, if available; and follow the raspberry and blackberry spray schedule outlined in the “Midwest Commercial Small Fruit and Grape Spray Guide.” (http://www.hort.purdue.edu/hort/ext/sfg/).

For more information on orange rust of brambles, refer to the “Midwest Small Fruit Pest Management Handbook” (http://www.ag.ohio-state.edu/~ohioline/b861/index.html) and “Compendium of Raspberry and Blackberry Diseases and Insects,” published by the American Phytopathological Society, St. Paul, Minnesota.

II.Fungicide Programs for Freeze-Damaged Apple Orchards

Due to the April-May freeze damages, some apple orchards in northern Illinois have no crop. Regular fungicide spray program many not be needed in these orchards. Two major diseases that should be considered important are scab and powdery mildew. For disese management in such orchards, click here.

June 17, 2005
	I. Orange Rust of Brambles AOrange rust is the most important of several rust diseases that attack brambles. All varieties of black and purple raspberries and most varieties of erect blackberries and trailing blackberries are susceptible to orange rust. In the past two year severe infection of orange rust has been observed in commercial orchards in Illinois. Orange rust is easily identified shortly after new growth appears in the spring. Newly forming shoots are weak and spindly. Leaves on such canes are stunted and misshapen and pale green to yellowish. Within a few weeks, the lower surface of infected leaves are covered with blister-like pustules that are initially waxy but turn powdery and bright orange. These "rusted" leaves wither and drop by early summer. Young, apparently healthy canes, with normal leaves can be found toward the end of June. Unfortunately, diseased plants are systemically infected, and the fungus is present in the roots, canes, and leaves. Infected canes will be bushy and spindly, and will bear little or no fruit in the following season. To control orange rust:plant only certified, disease-free planting stock from a reputable nursery; before setting out new plants, remove and burn all wild brambles and any cultivated plants that are rust infected, including the roots; when the disease first appears in early spring, dig up and burn infected plants before the pustules break open and discharge spores; improve air circulation by thinning out healthy canes in the rows and keeping the planting free of weeds; plant resistant cultivars, if available; and follow the raspberry and blackberry spray schedule outlined in the “Midwest Commercial Small Fruit and Grape Spray Guide.” (http://www.hort.purdue.edu/hort/ext/sfg/). For more information on orange rust of brambles, refer to the “Midwest Small Fruit Pest Management Handbook” (http://www.ag.ohio-state.edu/~ohioline/b861/index.html) and “Compendium of Raspberry and Blackberry Diseases and Insects,” published by the American Phytopathological Society, St. Paul, Minnesota. II.Fungicide Programs for Freeze-Damaged Apple Orchards Due to the April-May freeze damages, some apple orchards in northern Illinois have no crop. Regular fungicide spray program many not be needed in these orchards. Two major diseases that should be considered important are scab and powdery mildew. For disese management in such orchards, click here. .