II. — Provisional Host-index of Australian Fongi. 



The list of Fungi, systematically arranged, enables us to classify them under their respective Host-plants. 

 Strictly speaking, it is only those which are parasitic, or which prey upon living plants, that should be included ; 

 but it is so difficult with onr present knowledge to distinguish between those which cause disease and those which 

 attack decaying or decayed parts, that I have given all the Fungi found upon any particular plant. While special 

 attention is paid to the Fungi occurring on the various vegetable products grown in the colony for commercial 

 purposes, as given in the Government Statist's returns, the Fungi on so-called " weeds " are not neglected, because 

 they may and often do pass over to the cultivated and tlierefore more delicate forms of vegetation. For example, the 

 Fungus causing " Club-root" in Cabbages, Cauliflowers, Turnips, Radishes, Kale, &c., also infests two of our common 

 weeds, viz., Shepherd's Purse (Cajjsella Bursa-pastoris, Moeuch) and Hedge Mustard (Sisymbrium officinale, Scop), 

 aud many similar instances could be given. This fact is strikingly put by Mr. Bailev, who says — "As we find in 

 the animal kingdom the wild man preferring sheep to kangaroo, the flying fox peaches to quandong, the grasshopper 

 the more succulent vegetation of our gardens to the dry herbage of the plains, so in like manner we shall doubtless 

 find from time to time blight-fungi, at present unknown, will come from tlie indigenous plants to exotic ones wliicb 

 may be more congenial to their development." 



There can be no doubt that many of the Fungi on our native vegetation will attack introduced plants, nml 

 it would be very desirable, both in the interests of science and of practical utility, to have a record of the Finigi 

 preying upon our native plants. I have seen some of our richest soils with the decaying roots of Eucalypts and 

 the mycelium of Fungi passing from them to the roots of orchard trees and causing their decay. 



The Host-index should serve various useful purposes. First of all, it will enable the intelligent grower to 

 determine with some degree of certainty the cause of the disease when it is due to a Fungus, and that is often the first 

 step towards its eradication. Thus, if his Peach trees are afEected with some Fungus disease on the leaves, he turns 

 np (he Index and finds two F'ungi recorded there. He then turns to the General Characters in the "Systematic 

 Arrangement " and can easily tell whether it is the " Peach-leaf Rust " or the " Leaf-curl." Or if his Cabbages and 

 Cauliflowers begin to turn yellow and the roots become distorted, he finds from the Index that it is due to a Fungus, a 

 knowledge of which enables him to battle with the disease. Having traced the disease to its source, he may find 

 treatment already prescribed in some of the Government publications, or can apply to the Department for advice. If 

 there is no record of the disease in the Index, then the grower knows it is a subject requiring investigation. 



Further, the Host-index may be used in assisting growers to "spot" diseases due to Fungi before they li;ive 

 spiead too far aud become established. A great many Fungus diseases are overlooked for a number of years and 

 allowed to spread freely before active measures are taken for their suppression, and thus what might have been easily 

 nipped in the Ijud is now difficult to eradicate; so that another important use of this publication will be to enable 

 Fungus diseases to be recognised at tlie earliest possible moment and action taken accordingly. 



Onion Moidd, Ergot in Rye and other Grasses, Powdery Mildew in Apple, and various other diseases, are not 

 recorded in Cooke's Handbook, and, presumably, have been neglected. 



A third use will be to assist in the carrying ont of any legislation which may be passed for the suppression of 

 Insect and Fungus pests. Many growers err in ignorance, because they are not aware of the disease being present until 

 it has got a firm Iiold, but now a record of the various Fungus pests is availalde. 



And there is a final purpose to be served which is not the least important. New diseases are continually 

 cropping np, and the sooner they are recognised the better. If the disease is not recorded in the Index there is a 

 strong probability of its being some new one, and then it can be traced to its source without delay. 



The names of the Host-plants are given according to Baron von Mueller's Second Systematic Census of 

 Australian Plants or Hooker and Jackson's Index Kewensis, as far as jmblished. Tlie Fungi belonging to Victoria 

 are indicated bv the letter Y. 



