NURSERY MANAGEMENT 279 



tures in the rose houses varied from fi2 to 'JO; in the car- 

 nation houses 54 to 60. The length of fumigation was 

 16 to 17 minutes. Good results in destroying aphis were 

 always secured in the rose houses, though sometimes 

 the foliage was slightly injured; in the carnation houses, 

 many aphis lived through the fumigation. Later experi- 

 ments showed that fumigation for green aphis on carna- 

 tions is not likely to prove successful at temperatures 

 below 60 unless the three-fourths ounce of cyanide is 

 used to 1,000 cubic feet and the time of fumigation in- 

 creased to 30 minutes ; perhaps not even then. 



376. Nursery tree trimming. — Stockiness is one of the 

 main points nurserymen aim to secure in their trees. To 

 obtain this they give the trees plenty of space, usually 

 not less than nine inches in rows three feet apart for 

 small trees, and 12 inches and 3^/2 to 4 feet for large 

 kinds which are to remain in the rows not over two 

 years. Greater space is usually needed for longer 

 periods. The first year the leaves should not be rubbed 

 from the tree stems, or the trees will grow too slender 

 and too tall. Should branching start too low. or should 

 there be Y-crotches, trimming will be needed. By fall 

 of the first year stock budded in the North the previous 

 summer and that started from root grafts in the spring, 

 should be four or more feet tall. That budded in the 

 South in June should be as tall or taller. 



In the spring the height is usually reduced to three or 

 four feet to form the head. Some nurserymen head as 

 low as 2 feet, or even 18 inches, to meet the increasing 

 demand for low-headed trees. Shortly after heading 

 back the earth is hoed away from the trunk bases and all 

 sprouts from crowns and roots cut off. The leaves that 

 appear on trunks and branches should not be removed, 

 because they are needed to ripen and develop the ad- 

 jacent wood and to help supply the roots with plant food. 

 The practice of rubbing them off early in the season can- 

 not be too strongly condemned. Trees deprived of these 



