190 THE GRAPE. 



J U I. Y. 



MILDEW. 



As this pest to the grape-grower commences its de 

 structive efiects with the first damp and muggy weather 

 h\ this month, and, if not timely checked, will ultimately 

 destroy the hopes of the cultivator, the subject requires 

 more than a passing notice, and at the risk of being 

 thought tedious, we again repeat an explanation. This 

 intruder is a fungoid plant, strictly parasitical in its na- 

 ture, requiring a living ^organism upon which to com- 

 mence developing. It is also entirely dependent upon a 

 peculiar state of the atmosphere, otherwise the sporules 

 or minute seeds which float unperceived in the air, cannot 

 vegetate. The first indication of mildew is manifested by 

 brown spots on the leaves, generally along the mid-ribs 

 and larger reticulations. The fleshy parts, so far as affect- 

 ed, are soon destroyed, and immediately after this, the 

 fungus develops its fructification in the form of a white down 

 on the under side of the leaf. In this state tho spores 

 are ripe for future growth ; and so quick is this action, 

 that in two or three days thej will spread over a great 

 part of the leaves and fruit, causing the entire vines to be 

 irreparably injured for the season. 



Our own native kinds, such as Isabella, &c., having a 

 hardier constitutional power, are only slightly, and some- 

 times not at all aff*ected, but owing to our extreme 

 chano-es, we are not able to cultivate the exotics in the 

 open air to perfection, except in the best sheltered city 

 yards. After many years' close observation, I have in- 

 variably found that a sudden check to the circulatory 

 jiiedium of plants renders not only the grape-vine, bui 

 most other, very liable to be infested with mildew, while, 

 if :i healthy and vigorous growth be mamtained, they art 



