7S8 FUNGI 



In many cases small portions of the surface of the berries are 

 destroyed, and the fruits become deformed and cracked, after 

 which decay, due to the entrance of saprophytic organisms, 

 sets in. 



(iv) Various injurious Oidium-forms are met with, which 

 appear to belong to the Erysiphaceae, but which cannot be 

 assigned to any definite genus, because their perithecia are 

 unknown. To this class belongs Oidium Balsamii Mont., so 

 common in some seasons upon turnips, swedes, rape, and other 

 cultivated species of Brassica. 



The mycelium spreads over the whole plant, and the barrel- 

 shaped conidia are sometimes produced in such quantities that 

 the clothes and boots of persons walking through a field of 

 diseased turnips or rape become chalky-white with the spores. 



Badly-aifected cruciferous plants give off a putrid odour, and 

 in several cases we have known sheep poisoned by feeding on 

 such diseased crops. 



Prevention and Remedies for Mildews. — The methods 

 described under 'Hop-mould,' pp. 749-753, are applicable to all 

 mildews. Every care should be taken to effectually dispose of 

 the dead refuse which contains the perithecia of these fungi. 

 Burning where possible is the best plan for destroying the 

 diseased stems and leaves. 



' Bordeaux mixture ' and washes containing sulphur, either as 

 such or in the form of sulphides of alkaline metals, are highly 

 beneficial in cases of mildew attacks. 



Ex. 321. — Make observations similar to those of Exs. 318 to 320 on rose, 

 pea, grass, vine, and chrysanthemum mildews ; pay special attention to the 

 form and size of the conidia, the number of these on each conidiophore, and 

 the form, size, and contents of their perithecia and ascL 



4. 'Ergot.' — An important parasite belonging to the Hypo- 

 creacecB, another family of the Ascomycetes, is the ergot fungus, 

 which attacks the ovaries of grasses and cereals. 



