PINACE.E 455 



climatic conditions, on sweet, deep light loam, or on sandy soil 

 with a well-drained subsoil. It also succeeds on dry sandy soil 

 on rocky mountain slopes, in ravines, and on low land where 

 the soil approaches clay in consistency, but it is not adapted for 

 very limy soils. If it is planted in any position where water is 

 inclined to lie, even though the ground may not be water-logged 

 for more than a few weeks, open drains must be made at frequent 

 intervals. Although it withstands considerable exposure inland, 

 it is less suitable than several other species for planting near the 

 coast for withstanding the full force of strong winds direct from 

 the sea. It is sometimes planted under forest conditions in the 

 British Isles with good results , but where the climatic conditions 

 are very mild and on the dry side, or in places where the soil is 

 unsuitable and the trees do not grow freely, it is very subject to 

 attacks of the Weymouth pine aphis. An area of 6-7 acres of 

 timber cut in Windsor Forest in 1916, at an age of 70 years, 

 yielded over 4,000 cubic ft. of timber to the acre, quarter girth, 

 under bark measure ; the largest tree containing 107 cubic ft. 

 of timber.^ 



Natural regeneration is satisfactory in America, good seed 

 years occurring every 4-7 years, with a small annual seed pro- 

 duction. It is stated^ that 10,000 plants may be expected from 

 every pound of fertile seed sown, and that although the best 

 results follow the use of new seed a fair percentage of seed kept in 

 cold storage for 5 years remains fertile. Seedlings and young 

 trees withstand a good deal of shade, but as the trees advance in 

 age they require more light and must be able to dominate com- 

 panion species by the time they are 40-50 years old. In America 

 spacing 6 ft. by 6 ft. is recommended for plantations, either pure 

 or as a two-thirds mixture with one-third of chestnut, oak, 

 spruce or maple. One of the best combinations appears to be 

 Weymouth pine and Picea excelsa, the two trees cleaning each 

 other well. Spaced similarly in the British Isles it is probable 

 that the lower branches would become too large to clean naturally 

 and pruning would become necessary. In America when spaced 

 6 ft. by 6 ft, the first thinning is required at the end of 30 years, 

 but when planted 4 ft. by 4 ft. thinning is necessary at the end of 

 10 years. The bark of young trees being very thin, sudden 

 exposure to hot sun must be avoided. As an ornamental tree it 

 has much to commend it, but it should not be planted in hot or 

 very dry places. 



The Weymouth and several other five -leaved pines are subject 

 to serious injury by various diseases. In the British Isles, the 

 Weymouth Pine Rust (Cronartium ribicolum, Dietrich) sometimes 

 causes serious loss. There are two distinct stages in the life 



^ Quarterly Journal of Forestry, Oct. 1916, p. 286. 



2Pinchot, For, Ser. Circular, 67, U.S. Dept. of Agric. (1907), 



