ANNUAL REPORT, 1937 



35 



3 months to the marketing season. The same interv^al-temperatures proved safe 

 for leaf cuttings. Sanitary and cultural methods within the limits of good plant 

 growth and commercial practice are not effective in arresting the progress of the 

 disease. 



2. Apple Scab Control. Five brands of wettable sulfur of different sulfur 

 content ranging from 30 to 98 J^ percent, and varying in particle size from 0.9-6.3 

 microns to 3-4.5 microns with different brands, were compared on an equivalent 

 sulfur basis in a full schedule of treatments with the official spray schedule of 

 liquid lime-sulfur and wettab e sulfur for scab control and foliage tolerance. 

 The coarsest and finest wettable sulfurs gave the poorest and best control, res- 

 pectively. Injury to the foliage, which was severe, occurred only from liquid 

 lim2-3ulfur. The materials and results are tabulated as follows: 



Material Sulfur Dilution Scabby .\verage Number of 



Content Pounds in Apples Infections per 



Percent 100 Gallons Percent Scabbed Apple 



Linco 55 3.2 No apples No apples 



Hood 98.5 1.8 13.3 3.3 



Magnetic 98.5 1.8 23.8 i .i 



Flotation 40 4.5 2.5 1.0 



Kolofog 30 6.0 8.3 5.0 



Official schedule 0.0 0.0 



3. Vegetable Seed Treatments. Soaking of celery seed in corrosive sublimate 

 solution (1-1000) for 20 minutes, usually recommended as a disease control 

 measure, was found in a series of tests to be definitely harmful to the seed. The 

 mean stand of plants was reduced approximately one half by the treatment. 



A test of different chemical treatments of vegetable seeds for damping-off 

 control was conducted and the results embodied with the data of previous years. 

 The preferred seed treatments for controlling damping-off, based on these tests, 

 are indicated as follows: 



Red Copper Oxide Semesan Zinc Oxide 



Beet Bean (snap) Bean (lima) 



Carrot Cabbage Parsnip 



Cucumber Cauliflower Radish 



Eggplant Corn Turnip 



Lettuce Onion 



M uskmelon Pea 



Pepper 

 Spinach 

 Squash 

 Tomato 



4. Resistance of Cucumbers to Powdery Mildew {Erysiphe cichoracearum DC). 

 This disease is a major problem in the culture of greenhouse cucumbers. A test 

 in cooperation with Prof. R. E. Young in search of resistance among 169 types of 

 cucurbits, mostly cucumbers, supplied by the Division of Plant Exploration and 

 Introduction, United States Department of Agriculture, showed a high degree 

 of susceptibility by all except Cucumis Melo L. var.flexuosus Naudin, the snake 



' melon, which was resistant but which does not cross with the cucumber. Studies 

 will be made of other types. 



5. Copper Spray Tests on Cucumbers, Muskmelons and Tomatoes. These crops 

 were used to test the merits of newer copper fungicides. This year Copper 

 Hydro 40, Coposil, Dow Copper Fungicide, Basi-Cop, Cupro-K, Cuprocide 54, 



