Feb. 24, 1919 



Angular-Leaf Spot of Tobacco 



221 



the substation informed us that the tobacco on these backward plots 

 became spotted later with the advent of additional rainfall and cool 

 nights, and that the second growth tobacco from the early harvested 

 plots also became diseased. 



CHARACTER OF LOSSES 



A demonstration acre of tobacco at the substation at Charlotte Court 

 House was severely spotted in 191 7, much more so than in any previous 

 years. The yields from this acre were obtained to determine the varia- 

 tion in yield and grade between 191 7 and the average of preceding years. 

 The data obtained are included in Table I. The yield of the average 

 year was determined from demonstration acres for the years 191 3, 191 4, 

 and 1 91 5. Complete data for 191 6 were not available, but the total 

 yield for this year, 1,005 pounds, shows a close agreement with the three 

 preceding years. The effect of the disease is shown both in a reduction 

 in yield and in grade. The yield from the acre in 191 7 was 212 pounds 

 less than that of the average year, or approximately 80 per cent of the 

 average. The yields in the different grades for 191 7 show a loss in 

 weight in all of the three highest grades and a strong increase in the 

 lowest grade. There were approximately 40 per cent more sand lugs 

 in 1 91 7, in proportion to the higher grades, than in the average year, 

 and the percentage of longs was slightly greater. The gain in the sand 

 lugs was made up by losses in the two middle grades, good lugs and 

 shorts. The total loss in weight was 20 per cent, and the loss in grade 

 approximately 40 per cent. 



Table I. — Variation in yield and grade between severely spotted tobacco in igij and the 

 average of three preceding years of light spotting 



Grade. 



Average 

 year. 



Average 

 year. 



Difiference between 

 191 7 and average 

 year. 



Sand lugs. 

 Good lugs . 



Shorts 



Longs . . . . 



Pounds. 

 495 



155 

 190 



Pounds. 

 205 

 290 

 346 



Per cetit. 

 58.9 



18.5 

 22. 6 



Per cent. 



19. 4 

 27. 6 



32- 9 



20. I 



Pounds. 

 + 290 



— 290 

 -191 



— 21 



Total . 



840 



1,052 



Per cent. 



+39- 5 

 — 27. 6 

 -14.4 

 + 2.5 



DESCRIPTION OF THE SPOTS 



The spots are found only on the leaves, none on stems or floral parts. 

 They are scattered over the entire leaf surface, between the larger veins, 

 or are crowded in irregular groups. They are usually bordered by viens 

 whicji act as barriers against further enlargement. More than 500 spots 

 may be counted on the average leaf of a heavily infected plant. They 

 are about equally prominent on the upper and lower leaf surfaces. The 



