seed with a fungicide and to put on an inoculant, plant pathologists recommend in- 

 oculating the seed first, then applying the captan or thiram fungicide to the seed 

 WITHIN TWO HOURS BEFORE PLANTING. 



Seed quality and vigor are also down this year, so it will pay to prepare as good 

 a seedbed as possible and to plant at a shallow depth in warm soil. After that, 

 all we can do is hope for fair weather so that germination will be rapid. Many 

 farmers will be adjusting their planting rate to bring these factors into balance. 

 This year, extra care in planting should pay large dividends. 



ALFALFA 



Bacterial wilt and Phytophthora root rot. These are prevalent diseases in fields 

 with poorly drained, heavy soil. Phytophthora root rot develops rapidly during 

 cool, rainy weather. Plants in low spots wilt, wither, and die with little or no 

 stunting. Look for crown and taproot tissue that is soft, water- soaked, and yellow 

 or tan. Infected plants can often be pulled easily from the soil, leaving most of 

 the root system behind. The same Phytophthora fungus causes alfalfa seedlings to 

 damp-off before or after emergence. There are no good controls for Phytophthora 

 root rot, except to avoid planting in low areas subject to flooding and to follow 

 recommended cultural practices in order to keep plants growing as vigoruously as 

 possible. 



Bacterial wilt. This can be severe in low, poorly drained areas. However, the 

 relatively low number of alfalfa stands that are over three years old and the de- 

 velopment of resistant varieties now keep bacterial wilt from being the major prob- 

 lem it used to be. The causal bacterium is spread by surface water, equipment, and 

 infected hay. It enters through wounds produced by winter injury or mechanical dam- 

 age. Look for stunted, yellow plants that grow slowly and have a bunchy appearance. 

 Affected plants may wilt during midday, recovering at night for a short time. During 

 warm, dry weather, wilting and dying can occur rapidly. For positive diagnosis of 

 bacterial wilt, cut through the taproot at right angles and look for scattered yel- 

 lowish to brownish dots or a ring in the vascular tissue (normally a creamy-white 

 color) . To control bacterial wilt, grow one of many resistant varieties (see Re- 

 port on Plant Diseases No. 300) , or plan to keep an alfalfa stand for only two 

 years . 



Leaf and stem diseases. These are widespread following the recent cool, wet weather. 

 Spots of various sizes and colors develop on the leaflets, causing the leaves to pre- 

 maturely turn yellow and drop in large numbers. Several leaf -spotting fungi also at- 

 tack the stems, producing reddish-brown to black spots and girdling cankers. Then, 

 the foliage wilts and dies. The control for this disease is complex. Follow these 

 practices: (1) grow varieties resistant to common leaf spot. (2) Cut heavily in- 

 fected stands in the prebloom or bud stage, BEFORE a large percentage of the leaves 

 fall. (3) Plant certified, disease-free seed. (4) Where feasible, rotate at 

 least two years with corn, soybeans, or small grains free from volunteer forage leg- 

 umes. (5) Do not leave high stubble in fields or allow weeds to mat around plants. 

 (6) Maintain an adequate amount of potash in the soil. 



WINTER WHEAT 



Soil -borne mosaic. The top leaf may well be symptomless, while the lower leaves 

 show varying degrees of light- and dark-green mottling (especially when leaves are 

 held up to the light) or yellow streaks and blotches. Losses from soil-borne mosaic 

 will be greater this year than for the past several years. This mosaic is found in 

 poorly drained low spots. Infected fields have a patchy, or uneven, appearance. 



