44 TRANSACTIONS OP THE ILLINOIS 



One of the rot species, and the worst with us, is known by the 

 name of Plioma uv/eoJa, and the effect is by some called brown rot, 

 perhaps more often black rot. On the berry this shows itself at first 

 as a small, brownish, watery speck, which gradually increases in 

 size, now 'embracing one-fourth, now one-half, now, perhaps, the 

 whole of the surface. When a quarter of an inch or so acro.ss there 

 is a central dot of lighter color; after the discoloration of most of 

 the fruit, careful examination with the unaided eye, or by the help 

 of a hand magnifier, reveals multitudes of little pointed prominences 

 pressing up from beneath the skin. As the berry shrivels these be- 

 come more readly recognized, and it is not hard to make out that 

 each of the little pustules opens at the apex, and sends out a minute 

 mass of white mucilage-like substance, either in the shape of a little 

 tendril or as a rounded globule. This mass consists of spores which 

 serve to propagate the disease. This same fungus sometimes works on 

 the leaves and young stems, but is not usually seen except on the 

 fruit. There is good evidence a second kind of spores is found dur- 

 ing the "winter on the old^ fallen berries, and that the summer's crop 

 comes from these. 



The other rot has had many names, owing in part to its diversity 

 of appearance, size, etc., under different circumstances. It is a severe 

 scourge to the vines in many parts of the old world, but it is not 

 nearly so common with us as the preceding. Many botanists now 

 agree in selecting as the proper scientific name, spliaceJoma arnpeU- 

 num, and the French common name of ''anthracnose" is perhaps 

 the best for us. Under the effects of the fungus the berry does not 

 really rot. A circumscribed spot is killed, but the part remains dry, 

 and the rest of the fruit continues its growth. After a time cracks 

 usually appear in the dry and hardened rind of the diseased area. 

 Sometimes the seed or seeds, still living and sound, protrude in part 

 from such cracks, presenting a curious appearance. The young shoots, 

 leaf -stalks, tendrils, etc., are often rendered scabby by the growth of 

 the fungus upon them in the same kind of circumscribed areas. A 

 vine badly affected in this way is a pitiable object. It is completely 

 demoralized, as they used to say of the tired boys in the army. Vigor 

 is displaced by weakness, green by purplish-black in spots often thick 

 enough to touch each other; smoothness of surface by brands and 

 scabs, and ultimately, perhaps, life by death. 



Now little as these depredators have in common to the eye of 

 the botanist, there is at least one particular of habit in which all agree, 

 namely, that the growth commences from without, and never far 

 from the point where the injury is afterward found. All are propa- 

 gated by spores borne in the air, none reproduce themselves in the 

 tissues of the affected plants. In no case are spores or other substi- 

 tutes for them taken upon by the roots; in no case do these repro- 

 ductive bodies circulate in the sap or fluids of the vine. If a berry 

 is directly affected, the spore germinates on the berry; if a leaf be- 



