Grafted Vineyards. 563 



Government guano, etc., have been miicli improved and again brought 

 to a productive condition after having become very poor. 



Climate. — As the American stocks grow in North America, where 

 they are indigenous, under very variable conditions of climate it was 

 to be expected that, j)ropagated under South African conditions, they 

 would not all do equally well. This has also been the experience m 

 Europe. As a clear example, one might instance Jacquez. This 

 stock has long been regarded in Erance as unsuitable because of its 

 insufficient resistance to phylloxera. In this coiuitr}-, as is dorrectly 

 shown in the 1912 and 1914 reports on our grafted vineyards, on a 

 great many soils Jacque:? is an outstanding stock. Under certain 

 conditions here, however, it has not proved sufhciently resistant, and 

 for that reason must not be used as a stock. The explanation of this 

 behaviour must undoubtedly be sought in our climate, which is 

 lesponsible for stimulating the growth of the vine and enabling it to 

 mature its wood better than is the case in Europe. The last-named 

 factor, viz., the maturing of the wood, which is more particularly 

 shown in the accumulation of resers^e food (chiefly starch) in the 

 roots, stem, and shoots of the vino exercises a very great influence on 

 its growth and productiveness. 



Climate, moreover, exercises a distinct effect on the life of 

 phylloxiera itself by providing mon'e suitable conditions for the 

 breeding of phylloxera in one season under a warm climate than in 

 an area with colder climates. This is the reason why phylloxera will 

 destroy the same stock grown under our climatic conditions more 

 rapidly than in the cold climate of middle Europe. We can, there- 

 fore, understand why it is so often the case that a grafted vineyard, 

 after a winter of low rainfall, followed by a dry summer, will suffer 

 from phylloxera and visibly deteriorate. 



It is true that the American stocks are much more susceptible to 

 changes of climate than the European vines. Keeping this in view 

 we must not accept blindly the results of experinients carried out in 

 other countries with American stocks ; it is necessary to test them 

 under our local conditions in order to establish their degree of 

 suitability. 



Cultivation and Manuring of the Soil. — The soil must be well 

 prepared (by trenching or deep ploughing) before the young vines 

 are planted so that they have a good start, and will be able to develop 

 their root system. If the soil is too wet it must be well drained 

 before the vines are planted. Further, the vineyard soil must be 

 worked in such a way that it is able to take up sufficient water and 

 lose the moisture during the summer as slowly as possible. This may 

 be accomplislied by keeping the surface soil loose and free of weeds. 

 The reason why these points are emphasized, although probably well 

 known, is because the investigation has revealed that a large number 

 of failures with grafted vineyards must be attributed simply to the 

 bad preparation and improper cultivation of the vineyard soil. 



It stands to reason ihat proper fertilizing will stimulate the 

 growth of the vine and enable it to produce to a greater extent 

 without weakening the plant and thus rendering it susceptible to the 

 attacks of phylloxera. Poor soils particularly require a good dressing 

 of manure each year. The practice which obtains among some 



