CONTRIBUTIONS PROM THE WISLEY LABORATORY. 217 



and Portugal. It is evident that under certain conditions, if the fungus 

 once gains a foothold, it is capable of causing very serious damage to 

 these popular plants. 



The genus Septoria, to which the fungus belongs, is a very large 

 one and contains many species which do considerable harm in a very 

 short time. Though the area killed by a single individual of the fungus 

 is usually small, yet the spores are produced so rapidly after infection first 

 takes place, and in such abundance, that the spread of the fungus is 

 rapid, and the destruction of the whole plant in the case of such a plant 

 as the Antirrhinum is a question of only a few days. 



The fungus which is the cause of the disease is not known to attack 

 any other species of plant, and has received the name of Septoria 

 Antirrhini Desm. 



Careful examination with a lens will reveal, scattered over the 

 yellowish spots on the leaves and stems, exceedingly small darker spots. 

 These are the fruit bodies of the fungus, and the spores, which are long 

 and narrow (fig. 82, c) and thickly packed within the fruits, escape when 

 ripe by a small pore at the apex. They can germinate at once provided 

 moisture and a suitable temperature are available. 



Since Antirrhinum majus has become naturalized in this country, 

 particularly in the south, if the disease should spread it will probably 

 prove very difficult to eradicate. Wild plants would serve as breeding 

 grounds for the fungus whence it would continually spread to the 

 cultivated ones. It would, therefore, be well to burn any plants that are 

 attacked badly so as to destroy the spores completely and quickly. 



As a means of protecting plants which have escaped, and the whole of 

 the plants in a succeeding year, spraying with Bordeaux mixture or a 

 solution of one ounce of potassium sulphide in three gallons of water 

 should be resorted to. Where only small groups of plants are concerned 

 hand sprayers may be used. Small, light and handy little spraying 

 outfits, producing a very fine mist-like spray of just the kind suitable for 

 such a purpose, may now be obtained. Where larger numbers are required 

 to be sprayed a knapsack sprayer answers the purpose best. 



As the fungus has not previously been found in this country a 

 description is appended : 



Septoria Antirrhini Desm. — Spots yellowish ; perithecia on both sides 

 of the leaf, very small, 50//,-70yu in diameter, rather prominent, numerous, 

 crowded or scattered, with an opening at apex ; spores cylindrical, 

 obtuse, bent or curved, 4-7-guttate, one-celled, 15-20//, x 2-2*5/*. On 

 leaves and stem of Antirrhinum majus. 



VOL. XXXV. 



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