GENERAL INFORMATION 23 



spores are formed, which are capable of withstand- 

 ing variations of temperature, and subsequently 

 germinating under favourable conditions. In other 

 cases sclerotia (see p. 4) are found. 



7. T^^ansportation of Spores — Wounds. — Spores 

 are distributed either by wind or otherwise, and on 

 germination set up new centres of infection. En- 

 trance to the plant is made easier by the presence 

 of wounds, as seen on page 20, and like the other 

 above-mentioned facts, favours non-extermination. 



Natttral Conditions Unfavourable to Spread of 

 Disease. — From a cursory glance it would appear 

 as though everything was in favour of the growth 

 of parasitic fungi ; fortunately such is not the case. 

 Dry cold weather retards their growth, the cutiniz(xl 

 (hardened) epidermis of the plant makes entrance 

 more difficult, and by far the largest bulk of disease 

 spores find themselves deposited in places unfavour- 

 able to their development. Furthermore, the ex- 

 tent to which some varieties of a particular species 

 of plants are able to resist disease attack, affords 

 evidence that parasitic fungi meet with natural 

 factors which limit very considerably the extent of 

 their ravaofes. 



Amount of Damage Done by Fungi. — The loss 

 which any particular farmer suffers from a fungoid 

 attack is in itself serious, but it is only when we 

 take statistics for the whole country that we fully 

 realize the amount of damage done. Take potatoes 



