Control Of Insects And Diseases

From the number of insects and diseases found on the grape, it would

seem that, literally, "pestilence walketh in darkness and destruction

wasteth at noonday" in the vineyards of the country. But not many of

the ills that grape-flesh is heir to are ever found in one region, and

the vineyard is seldom attacked by many diseases or insects in a

single season. There was a time, as we have said before, when

grape-growers we e so beset by pests which they could not control,

that viticulture was one of the most uncertain fields in agriculture.

But one brilliant discovery after another has brought the pests of the

grape under the hand of man until now there are but few that need

cause much expense in treatment or worry as to the outcome.



Plants cannot be attacked by diseases unless infection is permitted.

It follows that by proper sanitation most of the insect pests of the

vine can be kept out of the vineyard.



Vineyard sanitation.



By changing or modifying environment, immunity can be secured from

many of the pests of the grape and damage may be reduced with most if

not all. Cultivation, as has been noted under several insect pests and

one or two of the diseases of the grape, is an effective method of

eliminating grape pests. In the case of insects, it destroys the

insects themselves and the hibernating places as well. The vineyard

should never be kept in sod, but always under thorough and frequent

cultivation. Vineyard sanitation is greatly improved, also, if

cover-crops which remain green during the winter are planted after the

last cultivation. Cultivation should usually be preceded by deep

plowing in the fall or spring to turn under fallen leaves and weeds or

grass in which hibernating insects may pass the winter.



The surroundings of the vineyard should be looked after. Fence-rows

and waste lands which cannot be cultivated may often be burned over to

destroy the hibernating places of grape insects. As a rule, it is

unwise to plant the bramble berries or even strawberries in

vineyards, or adjoining vineyards, since these plants afford

hibernating places and food plants for some of the grape insects,

especially the destructive leaf-hopper. Lastly, precaution should be

taken by destroying all wild grape-vines near vineyards, as these

frequently harbor insects and diseases, the flea-beetle finding the

wild grape-vine almost a necessity to its existence.



Spraying.



Definite rules cannot be laid down for spraying vineyards the country

over. The literature on this subject is plentiful in any state in

which grapes are largely grown, within the reach of the grape-grower,

and is not difficult to understand once it is in hand. Every

grape-grower should secure and study the publications of the state

experiment stations having to do with the control of insects and

diseases.



The number of applications and the sprays to be used vary greatly in

different parts of America. On the Pacific slope the only application

yearly required in most vineyard regions is dusting with flowers of

sulfur for powdery-mildew. Several other pests may, however, from year

to year, or in one locality or another, require special treatment. In

the grape regions of New York, many grape-growers do not spray at all,

but these are usually slovens or procrastinators whose profits are

small and uncertain. In the grape regions of the northeastern states,

orderly vineyardists spray at least once with bordeaux mixture

(4-4-50) in which is put three pounds of arsenate of lead, no matter

how few insects and fungi are present. This treatment is given soon

after the blossoms fall. In more southern regions it may be necessary

to make a similar treatment soon after the first leaves appear, again

after the blossoms fall and every two weeks thereafter until the

grapes begin to turn in color, making as many as four, five or even

six applications in all. To these regular applications of bordeaux

mixture and arsenate of lead, contact insecticides, as some of the

nicotine preparations, may have to be added; or, for special purposes

as specified in discussing the several pests, cheap molasses is added.

It is doubtful, however, whether the grape can be grown with

commercial success where insects and fungi prevail and are so

pestiferous as to require annually more than two or three applications

of spraying mixtures.