The grapes of New York

by U. P. Hedrick

Probably the chief factor in determining the adaptability of a region to grape culture is temperature. Each of the different species and varieties of grapes requires a certain amount of warmth for its best development and can endure but a certain degree of cold. The temperature of a region is chiefly determined by latitude, altitude and proximity to large bodies of water, though variations in the surface of the country are often important modifying agents of temperature and especially influence spring and fall frosts.

The grape does best in an equable temperature and does not thrive in regions where there is a great daily range. Regions and seasons in which the temperature is comparatively low in the growing months of May, June and July and high, with much sunshine, in the maturing months of August, September and October, produce the best grapes in the latitude of New York. An average of from 55° to 65° for the first named period and of from 65° to 75° for the second are ideal temperature conditions for the grape.

This fruit is very sensitive to moisture conditions. Not only must the total rainfall for the year be taken into consideration but its distribution throughout the seasons must be considered. The grape does best with comparatively little rainfall. When the rainfall is the least possible amount for a good growth of vine the grape crop will be the largest, of best quality and most free from fungi. Wet seasons, and especially wetness during the months of maturing, are disastrous to both quantity and quality of grapes. Thus, in New York it is not possible, with most varieties, to produce good grapes if the average is above six inches each for the three growing months and five inches each for the maturing months. It is far better for the crop that it be as low as four inches for the first named period and two inches for the second period.

Superfluous moisture in the soil favors too great a growth of vine, checks and weakens the root system, prevents proper setting of fruit, and favors fungi, but hinders the multiplication of phylloxera. In particular, a comparatively dry soil is desirable for grapes because of its influence on the development of the root system. In dry soils large root systems are developed in the search for the water that the plant must have. When intense droughts occur plants that have stood in damp soils have not sufficient roots to supply the necessary water to the aerial parts and the vines suffer in consequence. Some species and varieties are better fitted for withstanding an excess of moisture than others.

The soil exercises a great influence in determining the suitability of a region for viticulture. Several factors act as soil determinants: (1) Fertility; (2) physical characters; (3) soil heat. It is necessary to study each species, and even their varieties, to discover their powers of adaptation to different soils and it is possible to indicate here the good and bad qualities of soils only in the most general way. In the discussion of species and varieties the soil preferences of the different botanical and horticultural groups will be stated more fully.

Great fertility, as a natural characteristic, is not necessary in grape regions. Fertilizers, and especially the use of stable manures and cover crops, can be made to supply very largely a lack of fertility. Soils naturally too rich produce an overdevelopment of vine. Some species, as Vitis rupestris, grow naturally in very poor soils, the habitat of the latter being dry ravines and stony places having comparatively little organic matter. The varieties of Vitis rupestris promise well for stocks upon which to grow other varieties in certain soils. In Europe calcareous or limy soils are not considered well adapted to grape-growing, but in America we often find very good vineyards on such soils.

The physical character of a soil has more to do with the welfare of the grape than fertility. Sand and clay are the two distinct types of soils usually found in general agricultural regions. As one or the other predominates soils take their character. So far as growth alone is concerned these two types of soil do not influence the vines much differently, but the fruit in quantity and quality is greatly influenced by them. According as to whether sand or clay is in excess a soil is loose or compact, retains or gives up water, and is warm or cool. A compact soil is made so by an excess of clay or of very fine sand. Grapes require a light friable soil and compactness is often a serious defect. Usually species and varieties with large, thick roots are better adapted to compact soils than those with small root systems, probably because the strong roots have greater penetrating power than the weak ones. Lightness and permeability of the soil may be influenced by subsoiling and through the use of stable manure and cover crops, but a hard soil is generally so ill adapted to grape-growing that this fruit should not be planted on it.

The heat-retaining properties of a soil must always be taken into account in growing grapes. The great preference which many varieties of grapes show for sands, loams, shales and gravels, depends largely upon the greater amount of heat found in such soils. In northern regions it is especially needful that the soil furnish an abundance of bottom heat for the grape. The removal of an excess of moisture is helpful in regulating soil heat; and, other things being equal, a well-drained soil is warmest.

Grapes grow more or less well in any soil adapted to fruit-growing. It is not true, even, that the grape is more particular as to soils than other fruits. But the necessity of having great quantity and high quality of fruit in profitable viticulture makes it very necessary to take their preferences as to soil into strict account.

Air currents are of minor importance compared with the other factors discussed yet are worthy of attention. They are chiefly of importance in grape-growing in the suppression of fungi. It has long been noticed that in regions where there are strong currents of air the dreaded black-rot and the mildew are not nearly so harmful. Winds may be beneficial, too, when they bring warm air, when moisture laden, when they keep frosty air in motion, and possibly they have an effect on some small insects as the leaf-hopper. On the contrary they may be detrimental when too dry, strong or cold. Natural or artificial windbreaks may greatly modify the effects of wind currents though their value is usually overestimated as their benefits are often offset by the undesirable conditions caused.