. Minnesota plant diseases. Plant diseases. Minnesota Plant Diseases. 59 the rest of the plant. Then arise the carbuncle-like swellings of the leaves. If a kernel of the cob is attacked it increases perhaps tenfold in size. During this increase of size the fungus is also gaining strength and keeping pace with its partner plant-part, and when the proper moment has arrived for the formation of its spores it proceeds rapidly and utilizes all the extra food stored up by the swollen host plant-parts and de- stroys the latter rapidly. Such a parasite stimulates its host to unusual activity for a lon
. Minnesota plant diseases. Plant diseases. Minnesota Plant Diseases. 59 the rest of the plant. Then arise the carbuncle-like swellings of the leaves. If a kernel of the cob is attacked it increases perhaps tenfold in size. During this increase of size the fungus is also gaining strength and keeping pace with its partner plant-part, and when the proper moment has arrived for the formation of its spores it proceeds rapidly and utilizes all the extra food stored up by the swollen host plant-parts and de- stroys the latter rapidly. Such a parasite stimulates its host to unusual activity for a long time and at the same time pre- pares to use to best advantage all of the nutrient material laid up by the host, delaying its destruc- tive effects until the most advanta- geous moment. Sometimes, as in oat smuts, the presence of the fungus is not determinable until harvest-time, when the fungus forms its smutty powder of spores in place of the grain. This is a very efficient meth- od of parasitism but, in some respects at least, the fungi producing grain rusts are even more capable. The smut produces but one kind of spore on its host plant and that is a resting spore for tiding the fungus plant over the winter season. The rust fungus can produce spores from early spring to autumn and is able to do this by forming different kinds of spores at different seasons. Such a rust will produce a spring spore, a summer spore, and in autumn a so-called win- j ter spore, the latter having the same function as the spore of the smuts. I This continuous production of spores Fig. smut-au accom- jg Qf coursc 3. vcry efficient dcvicc. plished parasite. After G. P. _ ^ Clinton. In addition to the multiplicity of spores the rust fungi often possess the stimulating powers al- ready mentioned for smuts. Such have also been described in witches'-brooms of red cedar and balsam fir. In the simpler. Please note that these images are extracted from scanned page images that may have been digital
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectplantdi, bookyear1905
