INSECT PESTS AND DISEASES 133 



plants in the center of the bench. Individually, the 

 plants were not too close, but about the time they at- 

 tained to the maximum of growth, those in the center 

 were naturally confined and little air reached them, 

 except overhead. After the benches were reduced in 

 width to four feet the trouble did not reappear, clearly 

 showing the disease was brought on by congestion and 

 an inability of the leaves of the plants in the inner 

 rows to^properly perform their functions. The remedy 

 lies, therefore, in a studied avoidance of anything that 

 will tend to overcrowd or prevent a free circulation 

 of air among the plants in all stages of growth. 



Stem Rot is another fungous trouble, and, as the 

 name denotes, the rotting of the stem brings about the 

 death of the plants. Its attack is denoted by a droop- 

 ing of the leaves of the entire plant as though it 

 needed water. In reality, the plant does need water, 

 but Is unable to take it up through the usual channels, 

 which have become filled up by the growth of a fungus 

 so that water cannot pass up to sustain the plant. 

 Eventually the cells of the plant tissue become filled 

 with fungous growth, and death soon ensues. An ex- 

 amination of an affected plant will show at, or just 

 above the ground line, a white mold encircling the 

 stem, but the source of the first attack is in the soil. 

 With the decay of the stem and the maturity of the 

 fungous growth, spores are formed which again germi- 

 nate and grow, if a suitable medium be at hand. Little 

 can be done to combat an attack, but it is most desirable 

 to destroy all plants affected, and especially not to use 

 the soil for a similar crop, as that is the source of 

 infection. The use of rank manure in making the 

 compost may bring on an attack of stem rot, as decaying 

 vegetable matter is usually full of this type of fungus. 

 Plants growing in the open ground, and previously 



