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The Asparagus Rust in Europe. 



That the rust has long been known in Europe is apparent from the 

 fact that it was first described there, although, like many other of our 

 worst pests of the field and garden, it appears to have never become so 

 troublesome in the Old World as with us. The disease is described 

 in most of the German and English books on plant diseases, but we 

 have been told by several well known German botanists that it has 

 no practical importance with them, occurring only rarely and not at 

 all extensively. Certainly no such general epidemic of the disease 

 as has recently occurred in this country ever appeared in Europe. 



A Natural Enemy of the Rust. 



Another parasitic fungus has been observed in many cases in con- 

 nection with the summer and fall stage of the rust, which does not, 

 however, attack the asparagus plant but lives upon the rust fungus 

 itself. It is therefore beneficial rather than harmful, since it must 

 act to a greater or less extent as a check upon the development and 

 spread of the disease. This fungus is one called Darluca FilumCa.st. 

 It consists of filaments which grow in amongst those of the rust and 

 develoj) in the pustules of rust spores little black conceptacles in 

 wliich the spores of the parasite are produced. These spores are 

 somewhat smaller than those of the rust and ooze out upon the sur- 

 face of the rust spots in great quantities, giving them a mouldy 

 appearance. We found this parasite especially abundant upon the 

 summer stage of the rust in 1897, as well as upon thefallstage both 

 this year and last. Halsted (loc cit.) and Johnson* have also 

 reported its occurrence and it could no doubt be found wherever the 

 rust has appeared. It is interesting to note that we have also found 

 the same parasite upon specimens of the rust from Roumania, where 

 the asparagus plant is said to grow wild. It is possible that this is 

 at least one of the agencies which have prevented any extensive devel- 

 opment of the rust in Europe. 



Halsted (loc. cit.) also describes another parasite, Tubercidaria 

 persicina Ditt., which he has observed upon the spring form of the 

 asparagus rust. "We have found several other fungi upon asparagus 

 plants, but they were mostly such as had already been weakened by 

 the rust and we do not consider these as diseases of any practical 

 importance. What appears to be the "leopard spot" disease 



*Bull. 50, Maryland Agri'l Experiment Station. 



