SEPTORIA 421 



hairy perithecia of the fungus can be seen with the aid of a 

 magnifying-glass. 



Perithecia globose, partly buried in the substance of the 

 stem, ornamented with long, black spines round the opening. 



Spores elliptical, hyaline, 5X3^. 



When plants are once attacked cure is impossible, as the 

 mycelium is deeply seated in the tissues before its presence 

 is indicated by the wilting and yellowing of the foliage. 

 Diseased stems should be cut out and removed to prevent 

 the spread of the disease. 



Pyrenochaetaferox (Sacc.) sometimes forms blackish patches 

 on the fading stems of potatoes. Perithecia furnished round 

 the mouth with more or less spreading, colourless spines. 

 Spores cylindrical, 8-9 X i /*. 



** Spores \-many-septate. 

 SEPTORIA (FRIES.) 



Perithecia usually grouped on discoloured patches of living 

 leaves, sunk in the tissue of the host with a projecting open- 

 ing ; spores long and slender, usually many-septate, hyaline. 



Eighty-five British species are recorded ; the majority grow 

 on weeds and wild plants, and are of no economic im- 

 portance. The discoloured spots on living leaves of many 

 trees, herbaceous plants and weeds, are caused by species 

 of Septoria. 



Tomata leaf spot (Septoria lycopersid^ Speg.) is respon- 

 sible for this disease, whose presence in this country was 

 first noted by Giissow. It was first observed on tomatoes in 

 the Argentine Republic. The fungus attacks the fruit, stem, 

 calyx, but more especially the leaves, which show small, 

 blackish-green spots concentrically arranged \ these spots soon 

 become confluent, and the leaves, which are rapidly killed, 

 curl up and hang loosely from the stem. The spots often 

 become ashy-grey, and the numerous minute fungus fruits 

 appear like fine black dots scattered over the diseased area. 



Spores hyaline, filiform, slightly bent as a rule, 5-9-septate, 

 70-110X3 /*. 



Giissow states that plants can be saved if sprayed imme- 

 diately the disease is noticed, with a three per cent, solution 



