APPEARANCE OF THE INJURED AREAS.

An examination of many canes on which injured or dead buds and shoots were noted, invariably showed blackened areas along the cambium layer, while the tissues of the canes were surcharged with water. The cut surfaces of the canes lacked the vivid green of the normal tissues, but rather were of a grayish tinge. The areas around the juncture of the buds with the tissues of the canes contrasted strongly as to the depth of color with those uninjured. The cut surfaces of the former instead of showing the normal vivid green were of a yellowish brown color.

IMMATURITY THE DETERMINER OF THE INJURY.

Whatever other conditions contributed to the winter killing of 1915-1916, the immaturity of the cane and bud tissues is the factor that determined the extent of the injury. The poorly matured wood was conditioned upon the climate of the previous growing and maturing periods. Local factors such as late cultivation, elevation, soil type and the moisture content thereof no doubt aggravated or lessened the extent of the injury.

SPRING FROSTS AND THEIR RELATION TO WOOD MATURITY.

The frost injury of May, 1915, that affected many vineyards, especially in the eastern end of the "Belt " was considered as solely influencing the subsequent killing of 1915-1916, but vineyards unharmed by the May frost suffered almost as severely as those that were severely frozen back in the spring. However examination of several vineyards that were so injured during May, lead to the conclusion that such as were pruned back severely, just after the freeze, suffered considerably more from winter killing, during the dormant season 1915-1916 than those unpruned. Here again the injury may be charged to immaturity, as the closely pruned vines developed but a few canes, which grew very rank.

UNSEASONABLE WINTER TEMPERATURES AND THE INJURY.

Just how much the unseasonable temperatures of the week of January 22-29 contributed to the killing is problematical. It is worthy of note that for 96 consecutive hours of this week, the average hourly temperature was 52.6 degrees. Brehm 35 shows that the

35 Brehm. Horticulturist 18:52-53.

Delaware comes to leafing after a mean daily temperature for 14 days of 52.41 degrees. In the Station vineyard, Delaware began leafing one day later than Concord in 1916, hence the effective initial temperatures must approximate the same. In view of these facts it is quite probable that the effective initial temperatures of January 22-29 holding for one-fourth of the time necessary to bring into leaf did start into active growth the tissues of cane and bud. Their immature condition rendered them much more responsive to high temperatures than they would have been had complete maturity been reached during the previous fall. The minimum temperature (-16 degrees) of the winter 1916 occurred in March, but if the tissues were no longer completely dormant it is possible that the earlier temperature of -13 in February might have been the fatal one.

Warm winter weather, which is not sufficient to affect the temperature of the soil, stimulates a flow of sap in the vine as well as in certain trees.

The starting of dormant buds into growth is due to the warmth they receive and is practically independent of root action. However Chandler 36 found that the scales of peach buds do not serve to protect them from low temperatures. The scales however may serve to protect the bud tissues from loss of water by evaporation. In view of this conclusion the actual injury to grape buds during 1915-1916, if it occurred immediately subsequent to the warm period of January, was probably due to excessive evaporation rather than the formation of ice crystals within the inter-cellular spaces of the tissue, with the resultant disorganization of the cell protoplasm. The writer did not examine the buds at the close of the abnormally warm period of January 22-29, hence it is not known how greatly they had swollen and how much the bud scales had separated.

RELATION OF NITROGEN, PHOSPHORUS AND POTASSIUM TO WOOD AND BUD MATURITY.

The experiment vineyards afforded abundant opportunity during the spring and summer of 1910 and 1916 to study any possible relationship between the kind of fertilizer treatment with bud injury. With certain crops potassium has been ascribed as hastening maturity, while with others it shows the opposite effect. Nitrogen p. 110.

36 L. c.

it is known delays maturity, while phosphoric acid on the other hand has been demonstrated as bringing some crops to early maturity, especially during a wet season.

The writer is unaware of any available data relating to these functions with tree fruits and more particularly the vine.

In the spring of 1910 as soon as it was seen that many buds had failed to start, an inquiry arose as to the possible effect of fertilizers upon wood maturity and winter killing of grape buds. Our counts were made in a section of Concord vineyard about 30 years planted, situated upon a loose gravelly-loam soil of great depth. This is naturally well drained and in time of drouth the vines frequently are affected by a lack of moisture.

TABLE VII.-COMPARISON OF FERTILIZER TREATMENT WITH THE EXTENT OF INJURY FOR THE YEAR 1915-'16.

The 3-acre area slopes slightly to the south with the direction of the rows. From east to west the topography is very uniform. In 1909 the crop on this vineyard averaged 4.5 tons per acre. The section is divided into 11 plats that in the spring had received various combinations of nitrate of soda, dried blood, muriate of potash, acid phosphate and lime.

RANGE OF INJURY IN 1909-1910.

The counts made in the spring of 1910 showed that the extent of injury did not vary beyond the error liable in making the count, between the various fertilized plats and the control rows. Each

plat indicated that about 50 per ct. of the buds were dead, and suggested that nitrogen, phosphorus, potassium or calcium had not influenced favorably or unfavorably wood and bud maturity. It may be contended that enough time had not elapsed between the applications and the maturing period to make the influence of the fertilizers felt.

Table VII presents a comparison of fertilizer treatment with the degree of injury for the year 1915-1916 in the same vineyard.

The counts from which the percentages were figured include all the fruiting buds reserved for producing the crop of 1916, with the exception of short spurs on wood older than two years that were reserved for a renewal of the vine framework. The fruit buds were borne on canes developed during the summer of 1915.

An examination of this table indicates that the injury ranged from 19 to 31 per ct. The differences between the variously treated plats are so slight, that they come well within the range of experimental error, and we thus conclude that no plant food element has indirectly influenced the injury in this vineyard.

Tables VIII and IX present similar counts made in the same season in two seven-year Concord vineyards situated on Dunkirk silt loam. The area of these is 3 and 4 acres respectively. The entire area was tile-drained before the vineyards were planted.

TABLE VIII.— WINTER INJURY ON THE PLATS OF SECTION 8, 1916.

TABLE IX.- WINTER INJURY ON THE PLATS OF SECTION 9, 1916.

Where the word tile occurs it is indicated that a run is located in the center of the plat and parallel with the direction of the

rows.

In vineyard 8 the range of injury varied from 25 per ct. to 39 per ct., while in vineyard 9 the range was from 28 to 41 per ct. In neither were the differences among the plats sufficient to warrant any definite conclusions as to the effects of fertilizers upon wood and bud maturity, and indirectly upon the degree of winter injury. Further the plats thru which the tile ran were apparently no better favored than those plats lying at the farthest point from the run. This clearly indicated one of two conclusions, either the entire area was sufficiently well drained, regardless of distance from the tile, or else the amount of water in the soil during the fall was evenly distributed over the plats. The former appears the more reasonable for in no case is a row of vines further away than 20 feet from the tile, while the average distance is considerably less. It is very probable that the draw of the tile in this soil type is considerably greater than the actual maximum distance here existing between the runs. The appearance of the entire area during the wet periods of the year indicates general good drainage.