Homeowner Plant-Disease Problems 



Early blight on tomatoes is now showing up in home gardens. Look for roundish- 

 to- angular dark brown spots, with angular rings or ridges within them. Affected 

 leaves turn yellow or brown and drop early, starting at the base of the plant. 

 Exposed fruit later sunscald. The same fungus may cause dark brown- to-black, 

 sunken, leathery spots on the "shoulders" of the fruit near the stem end. 



Control earl>- blight by applying maneb (mostly sold as Manzate, Manzate D, Ortho 

 maneb, Di thane M-22) or Dithane M-45 as sprays at 7- to 10-day intervals. If the 

 weather is rainy, shorten the interval to 5 days; if it is dry and hot, lengthen 

 the interval, up to 14 days. Thorough coverage of foliage and fruit is essential. 

 Multipurpose vegetable dusts and sprays usually have maneb as an active ingredient, 



Blossom- end rot on tomatoes can be found now wherever fruits are at least half- 

 grown. The bottom or blossom end of the fruit becomes dark brown- to-black, and 

 is sunken and leathery. Up to one-half of the fruit may be involved. 



The control for this disease is to water during dry periods. Where feasible, 

 maintain a uniform soil -moisture supply and promote steady growth. Mulch or 

 cultivate in a shallow fashion during dry periods, and fertilize adequately- - 

 based on a soil test. Avoid overfertilizing with nitrogen and potassium. Four 

 weekly applications of calcium nitrate, starting when the first fruits are the 

 size of golf balls, may help. Use 1/2 to 3/4 of an ounce per gallon of water. 

 Calcium nitrate may be added to the maneb used to control early blight. 



Cat face on tomatoes is another disease now prevalent in home gardens. The blos- 

 som end of the fruit is extremely malformed and scarred with irregular, swollen 

 protuberances and bands of scar tissue. The control is to grow locally adapted 

 varieties and use the same treatment recommended for blossom-end rot. Cat face 

 may be caused by drought or by high (95° F. or above) or low (55° F. or below) 

 temperatures that reduce pollination on contact with a hormone-type herbicide, 

 such as 2,4-D. The disease is due to poor pollination. 



Early blight on potatoes can be found now and will be increasing with summer 

 showers and heavy- dews. The symptoms and control are the same as those for 

 tomatoes . 



Blackleg on potatoes is common in Illinois following heavy rains and cold weather 

 in heavy, poorly drained soils. Affected plants are stunted, upright, and wilt- 

 ing, with curled upper leaves. The stem base may be an oily green, but it soon 

 becomes dark brown- to-blackish, slimy, and rotted. The seed piece is often de- 

 cayed, and such plants are easily pulled up. Blackleg commonly follows seed- 

 corn maggots, wireworms, white grubs, borers, hail, or other injuries. The only 

 control procedure is to plant the best blue- tag seed available and to control 

 insects . 



WEEDS 



Corn 



This year, 2,4-D injury- to corn seems to be more severe than ever before in the 

 history of 2,4-D use in Illinois. 



