CULTURAL DIRECTIONS 



405 



Because of its hardiness the Egyptian tree onion (top 

 onion) is a favorite throughout the North. For the ear- 

 liest bunching onions, the sets should be planted in the 

 fall at least six weeks before freezing weather, and 

 mulched if possible with manure, after the ground is 

 frozen. 



Considerable quantities of bunching onions are also 

 grown from seed sown in the open ground, for market- 

 ing during the summer. This method requires the free 

 use of seed, 20 to 30 pounds an acre. It is an economical 

 method of production, and good profits are possible when 

 prices are materially lower than for bunching onions 

 grown from sets. 



Bunching onions are sometimes prepared for market 

 in the field (Figure 51), but it is better to take them to 

 the packing shed, where the dead leaves can be removed 

 and the onions properly washed and bunched. From 4 

 to ID onions are tied in a bunch, the number depending 

 upon size and market requirements. 



548. Insects. — The imported onion maggot (Pegomya 

 cepstorum) is closely related to the cabbage maggot 

 (363). The carbolic acid emulsion treatment, previously 

 described, is probably the most effective applica- 

 tion. Rotation, however, is the most certain means of 

 avoiding loss from this enemy as well as from all other 

 insect and fungous pests of the onion. 



The onion thrip (Thrips tabaci) is often a destructive 

 enemy, especially in the South and in the Southwest, 

 where Bermuda onions are grown. It is very minute in 

 size, not exceeding 1-20 inch in length, and provided 

 with sucking mouth parts and bristle-like mandibles. 

 When present in large numbers thrips cause the plants 

 to turn brown and die. Spraying with kerosene emul- 

 sion is considered the most successful treatment. Bor- 

 deaux mixture also serves as a repellent. 



