Extension News

Ask the ISU Garden Experts About: Spots on Apples, Herbicides on Lawns and Harvesting Butternut Squash

8/23/2010

What are the black spots or blotches on my apples? 
The problem may be sooty blotch and flyspeck. Sooty blotch and flyspeck are two different fungal diseases that often occur together on apples. Sooty blotch appears as dark brown to black, one-half inch or larger smudges on the surface of the apple. Flyspeck produces clusters of shiny, round black dots. Individual dots are about the size of a pinhead. Environmental conditions that favor disease development are moderate temperatures and extended wet periods in late summer/early fall. 

Sooty blotch and flyspeck live on the surface of the fruit. Damage is mainly cosmetic. The apples are still safe to eat. They’re just not very attractive. 

Cultural practices and fungicides can help control sooty blotch and flyspeck. Proper pruning of apple trees and thinning of fruit promote drying and help reduce disease severity. Fungicides also may be necessary. 

If control measures fail, sooty blotch and flyspeck can be removed with vigorous rubbing. 


When is the best time to apply a herbicide to the lawn to control dandelions and other broadleaf weeds? 
Fall (mid-September through October) is the best time to control perennial broadleaf weeds in the lawn with broadleaf herbicides. In fall, perennial broadleaf weeds are transporting food (carbohydrates) from their foliage to their roots in preparation for winter. Broadleaf herbicides applied in fall will be absorbed by the broadleaf weed’s foliage and transported to the roots along with the carbohydrates, resulting in the destruction of the broadleaf weeds. 

Broadleaf herbicides can be applied as liquids or granules. Before applying any herbicide, carefully read and follow label directions. 

When should I harvest butternut squash? 
Butternut squash are mature (ready to harvest) when the skin is hard (can’t be punctured with the thumbnail) and uniformly tan in color. When harvesting, leave a one inch stem on each fruit. 

After harvesting, cure butternut squash at a temperature of 80 to 85 F and a relative humidity of 80 to 85 percent for 10 to 14 days. Curing helps to harden the skin and heal any cuts and scratches. 

After curing, store butternut squash in a cool, dry well-ventilated location. Storage temperatures should be 50 to 55 F. Do not store squash near apples, pears or other ripening fruit. Ripening fruit release ethylene gas, which shortens the storage life of squash. 

When properly cured and stored, the storage life of butternut squash is approximately two to three months. 

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Contacts :

Richard Jauron, Horticulture, 515-294-1871, rjauron@iastate.edu

Willy Klein, Extension Communications and External Relations, 515-294-0662, wklein@iastate.edu