10 Nov., 1917.] Notes on Down;/ Mildew. 697 



bunches, on which they may cause grey rot early in the season, or brown 

 rot later on, provided, of course, that weather conditions are favorable; 

 once the berries commence to change colour the stomata are closed, and 

 berry infection is no longer possible. The young bunches are somewhat 

 difficult to protect with spraying mixture; being hidden under the 

 leaves, this does not readily reach them; their waxy nature also causes 

 it to adhere less satisfactorily than to the leaves. For bunch protection 

 the copper-containing powders, to be described presently, are a very 

 useful adjunct to sjjrayings — being cheaper, they can be more frequently 

 applied, and by means of the bellnws or knapsack sulphurer they can be 

 blown into the centre of the vine, where the young bunches are situated. 

 Topping, to remove the unprotected tips, has been recommended; 

 it often defeats the object by promoting the growth of laterals, which 

 are just as dangerous. Nevartheless, in some cases it can do good, 

 especially when an invasion is under way, but before the sporulation 

 stage is reached — in other words, they must be topped less than seven 

 days after the rain which permitted their contamination. Working 

 the soil, by increasing air moisture, facilitates infection. Cultural 

 operations, and likewise irrigation, should therefore be suspended 

 whenever this is to be feared. 



Winter Treatment Useless. 



Though for both fungi preventive treatment can alone be depended 

 on, Mildew differs greatly from Anthracnose, which can best be com- 

 bated by the destruction of the resting stage in winter by the acid iron 

 sulphate swab. For Mildew, however, no winter treatment is of the 

 slightest use. The oospores of the fungus pass the winter in the soil 

 embedded in the more or less decomposed remains of affected leaves, 

 where they are beyond the reach of any treatment. It would obviously 

 be futile to swab canes or stems on which no wintering forms of the 

 fungus exist. 



Spray Mixtures. 



As regards copper sprays, either Bordeaux mixture or copper soda 

 is good. The former is to be preferred, as it adheres better, and does 

 not deteriorate so quickly after mixing. It is largely used by orehardists, 

 but for vines it should be rather stronger than the usual orchard for- 

 mula (6-4-50). It should be 6-4-30 for Bordeaux, or 6-8-30 for copper 

 soda. The French way of mixing it is simpler than that usual here; 

 and with it one can more easily obtain a neutral mixture. If not 

 neutral, or nearly so, burning of the tender growths will result. Both 

 lime and soda vary a good deal in composition, hence the system of 

 weighing either of these substances does not always give satisfactory 

 result. 



The Commission recently appointed by the Societe Centrale d' Agri- 

 culture de I'Herault to inquire into the disastrous Mildew outbreak of 

 1915 in France, reported on this phase of the subject as follows: — "We 

 do not recommend any change in the usual preparation of Bouillies 

 (copper-containing spray mixtures) ; we will only state that, whether it 

 be a question of ordinary commercial (proprietary mixtures) or of 

 wetting bouillies* that they must contain a sufficient proportion of 



• Much attention has been paid to the wetting power of sprays; this can be increased by the 

 addition of soap and several other substances. 



