50 Experiment Station Bulletin 345 



state during the year. Orange King, a tangerine-fleshed determinate 

 variety, was distributed for test, as was Home Garden, an extremely 

 early variety that is comparatively small in size but of fine quality. These 

 are most valuable in home gardens and in parts of the state where the 

 season is shortest. A large number of foreign plant introductions are 

 being tested for disease resistance. Crosses between the most promising 

 of these and standard varieties have been made. Two additional genera- 

 tions, in addition to the field crop, were grown in the greenhouse, one 

 in the fall and one in the spring. (A. F. Yeager, J. R. Hepler) 



Developing Disease Resistance in Early Tomatoes 



In developing new early tomato varieties for New Hampshire, a pro- 

 ject carried out by the department of horticulture, a search has been 

 made to find parent stocks resistant to early blight. Of the four diseases 

 which are common in New Hampshire, early blight, late blight, blossom 

 end rot, and Cladosporium blight, the first is the most important. 



During the past year seventy commercial tomato varieties and selec- 

 tions from crosses were tested in the field and in an inoculation chamber 

 in the greenhouse for resistance to early blight. All of these were found 

 to be susceptible to the disease when placed under favorable conditions 

 for infection. Several other species and selections of tomatoes obtained 

 by others from South America have been grown in the greenhouse and 

 are now being tested in the field. 



Although none of the plants tested was immune to early blight, there 

 was a wide range in the amount of defoliation and injury caused by the 

 pathogen under field conditions. In general, those plants which had a 

 heavy fruit load in comparison with their foliage had the most disease. 

 As a result of these tests, and taking into consideration the findings of 

 other workers, it is believed that fruit load, available soil nutrients, spray- 

 ing with fungicides, water content of the soil, date of planting, and variety 

 —factors which hasten or induce physiological maturity in a plant— will 

 increase the susceptibility of that plant to early blight. (M. C. Richards, 

 R. W. Barratt) 



Muskmelon Breeding 



No varieties are ready for distribution as yet, but some high-quality 

 strains which possess perfect flowers and some extremely early, high- 

 quality melons not possessing perfect flowers have been isolated. The 

 combination of extreme earliness, high quality, and perfect flowers has 

 not yet been obtained in pure form. Attention is now being given to 

 the disease resistance of selections under test. (A. F. Yeager, J. R. 

 Hepler) 



Searching for Disease Resistance in the Muskmelon 



Investigations during the past year revealed that three diseases, pow- 

 dery mildew, downy mildew, and anthracnose, are of importance in 

 causing losses to muskmelon growers in New Hampshire. 



In the muskmelon breeding program, as carried out by the depart- 

 ment of horticulture, two crops of melons are grown in the greenhouse 

 during the fall and winter months. In the greenhouse powdery mildew 



