ANNUAL REPORT, 1945-46 59 



2. Carrot varieties and strains are planted each \-ear to evaluate the various 

 kinds, and these are generally tested for carotene during various stages of de- 

 velopment and after they have been in cold storage for several months. It was 

 plainly evident that the carrots were significantly lower in carotene in 1945 

 than they had been for a number of years. The only explanation that could be 

 given was the great amount of cloudy weather and excessive rainfall during the 

 growing season. 



3. Tomato varieties with a determinate habit of growth, such as Pennheart, 

 nearly always shed most of their leaves shortly after the ripening of the earliest 

 fruit. The drain of food reserves from the leaves b\' the heavy set of fruit has 

 been considered responsible for this condition. After various degrees of blossom 

 removal, it was clearly- evident that there was a negative correlation between the 

 fruit load on the plant and retention of its foliage. 



4. A peculiar chlorotic mottling of the leaves of greenhouse tomatoes has 

 appeared for several years, very similar to the symptoms of magnesium deficiency; 

 but large applications of magnesium as magnesium sulfate and high magnesium 

 limestone failed to correct the condition. High potash supplies in the soil often 

 aggravate magnesium deficiency in plants and the soil in question is well supplied 

 with potash. Applications of potash are now being withheld from some of the 

 plots in an attempt to determine whether an excess of potash is causing the 

 trouble. 



DEPARTMENT OF POMOLOGY 

 R. A. Van Meter in Charge 



The Influence of Various Clonal Rootstocks on Apple Varieties.^ (J. K. Shaw 

 and W. D. Weeks.) For three successive years, spring frosts ha\-e interfered with 

 a full crop in the large clonal rootstock orchard. As cold injury varied in severity 

 with variety and in different parts of the orchard, it has invalidated yield records, 

 but records of growth and bloom are still dependable. The trees are now growing 

 vigorously. Results of an experiment like this come slowl}', but the next few 

 years should show interesting results. 



An orchard of 256 trees of 16 varieties all on Mailing IX was planted in 1943. 

 There was some bloom and fruit last year and in 1946 nearly all varieties bloomed 

 freely and set a fair to good crop in spite of spring frosts. The orchard is on higher 

 ground than the orchard referred to above. There was little bloom on Northern 

 Spy and Red Spy, but only four trees of the remaining 224 trees of 14 common 

 varieties in the orchard failed to bloom. The trees have been in cultivation and 

 are growing vigorously. 



That Wealthy- is very much dwarfed on Mailing I while Mcintosh on the same 

 rootstock makes a t\pical semi-dwarf tree has been confirmed bj' further observa- 

 tions. 



Lethal Incompatabilities Between Clonal Stocks and Varieties of Apples. 

 (J. K; Shaw and W. D. Weeks.) Further studies of the lethal Mcintosh strain 

 R show that buds from the original tree of this strain failed to survive on the root- 

 stock Spy 227. Evidently the lethal factor is present in the original tree. Fail- 

 ure resulted when both strain R and the non-lethal strain G were budded together 

 on Spy 227. Evidently strain R is always lethal to Spy 227. Strain G wes 

 budded on a tree of strain R and buds from the resulting shoot were budded on 



^Two papers reporting on this project will appear in Vol. 47 of the Proceedings of the American 

 Society for Horticultural Science. 



