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THE PRODUCTION OF LAMMAS SHOOTS ON JACK PINE IN ONTARIO

1958; Canadian Institute of Forestry; Volume: 34; Issue: 3 Linguagem: Inglês

10.5558/tfc34307-3

1499-9315

J. B. Thomas,

Plant-Derived Bioactive Compounds

In mid-July, 1955, an unusual growth condition was noticed on jack, white, red, and Scots pine reproduction in the Lake Nipigon region of Ontario.Many lateral and some terminal buds set for 1956 broke dormancy, and new shoots from 1 to 6 inches long were produced.On these, new terminal and, in most cases, new lateral buds were set.This phenomenon was also observed at a number of points from Kenora in northwestern Ontario east to St. Williams in southern Ontario.Biisgen, Miinch and Thomson (1929) described this type of extra-seasonal growth on certain hardwoods and conifers in Europe as "lammas" shoot growth, the name being derived from the time of year at which it appears.In the United States, Jump (1938a, 1938b) investigated the forking caused by the development of lammas shoots on the main stems of red pine in plantations in New York State, showing that failure of the two sides of the fork to unite solidly permitted the entrance of fungal spores.More recently, Carvell (1956) and Littlefield (1956) have reported lammas growth on red pine planted in West Virginia and New York States, respectively.Carvell estimated that 76 per cent of the trees with lammas shoots had two or more strong leaders the next year capable of producing a permanent fork in the tree, thereby lessening its value for lumber.Lammas growth was most prevalent on jack pine in the Lake Nipigon region, the stems illustrated in Fig. 1 being typical of the various conditions encountered in late September, 1955.One or more of the lateral buds around the terminal of the two shoots in Fig l a and l b developed, but the terminal buds only swelled slightly and a few needles protruded from the sheath.The terminal as well as three laterals of the shoot in Fig. l c elongated, whereas only the terminal elongated in the shoot illustrated in Fig. Id.It was thought at first that repeated production of lammas shoots on young trees might have caused or at least contributed to deformities in jack pine reproduction being investigated at that time.Observations were continued, therefore, in the Lake Nipigon region during the 1956 growing season on 'Contribution No.