ANNUAL REPORT, 1945-46 21 



and for soil conservation, is increasing. One-node cuttings responded well to 

 powder-dip treatment with indolebutyric acid, but many cuttings died after 

 rooting if taken as late as September. 



In work with the Department of Pomology on the propagation of apple dwarf- 

 ing stocks, cuttings of Mailing No. 4 rooted well if taken in early May and given 

 powder-dip treatment with indolebutyric acid. 



Observations on the subsequent growth of rooted cuttings of white pine were 

 continued in the field. They appear to be developing into normal, well-formed 

 young trees. 2 



Surface watering was compared with subirrigation as factors affecting rooting 

 of cuttings of conifers. Cuttings of hemlock, Hinoki cypress, two species of fir, 

 and two species of spruce taken in November rooted better in sand watered from 

 above than in sand subirrigated. 



Work on the propagation of the rose by cuttings, initiated at the request of 

 florists who could not obtain grafting stock, was concluded and results published.^ 



Tomato Leaf Mold Caused by the Fungus, Cladosporium fulvum Cke. (E. F. 



Cuba, Waltham.) Four tomatoes resistant to leaf mold were developed to de- 

 sirable commercial type and released for commercial trial for the fall growing 

 season of 1945. These types were designated Improved Bay State, Improved 

 Vetomold-121, Leafmold Resistant Marglobe, and Leaf Mold Resistant Waltham 

 Forcing. Resistance to the fungus was derived from Plant Introduction No. 

 112,215, a Pimpindlifolium type from Educador. These tomatoes are con- 

 sidered acceptable by the growers. The resistant Marglobe cross is particularly 

 promising. 



Four similar tomatoes which derived their resistance from Plant Introduction 

 No. 129,882 from Peru are now completely susceptible to the disease. Other 

 named varieties developed for resistance have also acquired complete suscepti- 

 bility; namely, Globelle, Veteomold, Vetomold-121, and Bay State. 



Varieties introduced to the trade as resistant, apparently have but a limited 

 period of utility before the advantage of resistance is completely lost. Apparently, 

 this is due to the increase in the virulence of the fungus during its culture on 

 successive generations of resistant hosts. Loss of resistance is anticipated in 

 the types derived from Plant Introduction 112,215, and newly released to grow- 

 ers for trial. 



The cross of Prince Borghese, an Italian esculentum paste type, with L. 

 peruvianiim outcrossed to Pan America (No. 44 B 292), and of the same cross 

 backcrossed to Prince Borghese (No. 44 B 293) by W. S. Porte, United States 

 Department of Agriculture, are now the subject of study. L. peruvianum is 

 highly resistant to Cladosporium fidvum (Mass. Agr. Expt. Sta. Bui. 393:7, 1942). 

 L. peruvianum and the wide range of phenotypes in the above crosses are also 

 being studied for their reaction to the rootknot nematode. 



Causes and Control of Decay of Squash in Storage. (E. F. Guba, Waltham.) 

 Six plots of squash were grown, each of the same number of plants and identical 

 areas of land. These plots yielded 3871, 3628, 3844, 4935, 3676, and 2742 

 pounds of squash, respectively. 



Hubbard and Butternut squash from plots sprayed five times with Bordeaux 

 4-4-50 combined with 1 pound calcium arsenate were practically disease-free at 

 harvest, in contrast to the squash from plots not sprayed with fungicide, which 



2a manuscript on "The Vegetative Propagation of White Pine" has been prepared for publi- 

 cation. 



^A paper, "Propagation of the Briarcliff Rose by Cuttings" by \V. L. Doran, was published in 

 Florists' Exchange 105:11:7, 21. 1945. 



