1054 EXPERIMENT STATION EECORD. 



prevent excessive rust infection all rusty flax straw be thoroughly composted 

 or burned and that rotation of crops be followed. 



In his work with wheat, 401 different strains were under investigation, and all 

 the i)lats were given every possible chance to become infested with the common 

 wheat diseases. 



An experiment was carried on to determine the effect of soil sterilization, in 

 which the soil to a depth of 14 in. w^as sterilized and afterwards returned to 

 the plat and seeded to wheat. The yield of straw and grain on the sterilized plat 

 ^A'as above the normal growth of any near-by field crop, and the yield the second 

 year after sterilization was more than one-third greater than a similar non- 

 sterilized plat. 



A brief account is given of experiments on the fertilization of clover and 

 alfalfa, in which areas of red and white clover and alfalfa were covered with 

 small meshed wire screen to exclude the larger insects. The results showed 

 that alfalfa could partly fill under such conditions, while white clover produced 

 about one-third as much seed under the screen as in the open, and only 1 head of 

 red clover produced any seed. 



In continuation of previous experiments, the author reports on tree feeding, 

 stating that his experiments have progressed sufficiently far to permit a state- 

 ment that formaldehyde, copper sulphate, and iron sulphate, when properly 

 applied, tend to hasten the recovery of apple trees from sun-scald and sour 

 heart, to check the development of apple blight, and may hold the plum-pocket 

 disease in check. The method of applying the solution is fully described in a 

 previous report (E. S. K., 16. p. i:>l ). Brief notes are given on a plant survey 

 oi the State, fungus diseases, weed and seed laws, etc. 



The wintering of grain rusts, A. H. Christman {Trans. ^Vis. Acad. 8ci., 

 Arts, and Letters, 15 (1904). pt. 1. pp. 98-107). — Tlie author gives a review of 

 observations made by different investigators on the wintering of cereal rusts. 

 In order to test the ability of rusts to winter as mycelium and uredospores in a 

 latitude farther north than reported by others, he undertook a series of observa- 

 tions on several of the common rusts through the winter of 1902-.'l 



Well rusted plants could easily be found late in November, and during the 

 winter and early spring material was gathered from rye, wheat, blue grass, 

 and oats, some of the plats being protected by a covering of snow, while others 

 were exposed during a greater part of the wintei*. Water cultures were made 

 of the uredospores, and the germination of the spores as well as the maximum 

 and minimum temperature of each da.v are shown in tabular form. Spores 

 were germinated on evei'y day noted except in one instance, where they were 

 collectetl on February 18. It appears from the table that in the latitude of 

 Wisconsin, and with a period of 3 months during which the temperature scarcely 

 rises above the freezing point, viable uredospores may be obtained at practically 

 any time during the winter. 



It was noted early in the winter that in the case of badly rusted grain many 

 of the leaves exhibited pale spotted areas, and sections of these showed the 

 presence of mycelium and luideveloped spores. 



Continuing his observations, the author found that in the spring of the year 

 there were 2 distinct outbreaks of rust, the first occurring on the old winter 

 leaves within 2 weeks following the first warm weather, while the second crop 

 of uredospores did not appear until after the development of the first spring 

 leaves. He found by experiment that in the cool weather of the spring the 

 incubation period following inoculation is usually lengthened to between 3 and 

 4 weeks. The winter leaves die early in the spring and with them the winter 

 mycelium, but not until it has produced uredospores which inoculate the new 

 leaves. Between the dying of the old leaves and the appearance of rust on the 



