302 STATE BOARD OF AGRICULTURE. 



STATE FUNDS, 



Bean Disease Investigations: 



The Avork on bean diseases lias coiithuied along previously outlined 

 lines. AVoik of llie last tiseal year has been eoneentraled on the testing 

 of seed beans from the western districts. Formal rejjort on this inves- 

 tigational work is snbmitted by Mr. Muncie. 



Potato Disease Investigations: 



The work on the Fnsariiun Wilt disease of potato was continued 

 thronghont the summer of 11)1 G by Mr. R. W. Goss. While definite ad- 

 vance was secured in laboratory studies, following lines outlined in the 

 1916 report, the field work was greatly interfered with by the drought 

 of July and August. 



Fusarium wilt shows two aspects under Michigan conditions. The 

 first is a rapid wilting in which the vine dies before the tubers are ma- 

 ture — usually only half grown. The second form manifests itself at the 

 elo.se of the growing season and may cause the dying of the potatoes in 

 an entire field. The tubers from the potatoes showing the first type of 

 disease are typically pointed at the ends and show deep Fusarium wilt 

 markings. The tubers in the second aspect are nearly normal except 

 for a slight browning or yellowing of the vascular system. 



The observations of the last three years seem to warrant the state- 

 ment that the first aspect of the disease comes when affected tubers are 

 planted and the fungus grows from the mother tuber directly into the 

 young sprout. 



The second type of trouble comes about from invasion of the root 

 system by the parasite followed by a tardy wilting and gradual invasion 

 of the tubers. Tubers thus invaded produce the virulent type of wilt the 

 next year. 



Such observations coupled with the discover}^ of Avhat seems to be 

 Fusarium oxysporum in native Michigan soils accounts for the high per- 

 centage of infection which is present in our sandy fields and also points 

 out why under conditions of drought (which leads to death of the roots) 

 infection of the second type may occur in 1)0-100% of the plants. 



A field of potatoes was seen at Cheboygan last year in which about 95% 

 of the vines had wilted with Fusarium Wilt. Mr. H. L. Lewis, graduate 

 assistant in the department was sent to Cheboygan to select what 

 seemed Fusarium resistant hills from the plants which had remained 

 alive. About 300 hills Avere secured and these have been planted in soil 

 known to contain the wilt organism. It may sometime be possible to 

 secure a resistant strain for planting which will combine with desirable 

 varietal characteristics resistance to disease. 



Work was also done on the Black Leg of potato. This disease is wide 

 spread in the Upper Peninsula and is as yet extremely localized in the 

 Lower Peninsula and apparently on introduced seed. Work needs to be 

 done to show ^vhether the germ can winter in the soil, and whether it can 

 tolerate the climate of lower Michigan. A start on this work has been 

 made. In experiments made so far in cooperation with the Bacteriology 

 Department, the germ could not be isolated from soils heavily infested 

 two mouths previously. The soil solutions were extracted by the oil 

 pressure method and platings were made. 



The results of the study of epidemics of Late Blight of 1912 and 1915 

 were reported before the Botanical Society of America in New York 



