REPORT OF THE BOTANIST. 79 



We should say cut them oif -whenever one sees them. The most favorable time is 

 late iu autuam, before the ascospores are ripe. But it must not be forgotten that 

 the conidia ripea in early summer, and, if the knots are seen in the spring, they 

 should be cut off at once. 



Not only should diseased branches of cultivated cherries and plums be removed, but 

 all means should be taken to destroy the choke cherry, the bird cherry, and the wild 

 }>him, in the neighborhood of orchards. As a supporter of this disease •' the choke 

 cherry is a most dangerous enemy and should be destroyed. It is quite time that it 

 v.-as generally understood that many of our herbaceous and shrubby plants cause, or, 

 at any rate, iucrease disease in our vegetables and fruit trees. The farmer destroys 

 ( ;it('rpillars vrhereer and whenever he finds them; xrhy should he not also cut dowii 

 aud destroy all trees and shrubs -which carry a contagious disease into his fruit or- 

 chards. 



In respect to the smnt of Indian corn, which probably causes a greater 

 loss to our cereal crops than any other fungus, the same practice must 

 be followed as iu the case of the black knot, namely, the total desti'uc- 

 tiou of the affected parts. It has been demonstrated that the fungus 

 c;niJ;iijg tbis disease ( Ustilago Zecc Mays) enters the corn -^hile yet young, 

 tender, aud gcrmiuatiag. When fully established within the supporting 

 plaut the fuugus coutinues to live at its expense and grow with its 

 growth, extending upward through the stem as the latter elongates, 

 until the proper time comes for itl:o break forth from the excrescences 

 which it forms, and perfect a new crop of spores. The spores are pro- 

 dnced indiscriminately upon the leaves, stem, and flowers of the com, 

 but cbielly upon the latter. Soon after the tassels appear the planter 

 should go through the corn-field and carefully examine the stalks for 

 the peculiar aud well-known excrescences that are the first outward 

 manifestation of the presence of the fungus, and cut off aud burn every 

 excrescence. He may do little toward saving the present crop, but in 

 this way he will prevent the dissemination of millions of these fungus 

 spores, and do much toward the prevention of the continuance and 

 spread of the evil.* 



The soaking of seed wheat in a solution of strong brino or blue vitriol 

 for the prevention of smut of wheat is of no avail in the case of the smut 

 of Indian corn, as shown by the experiments of Prof. W, A. Henry, t If 

 the ground were absolutely free from the spores of corn smut, the soak- 

 ing or cleaning of the seed would, most likely, be a further safeguard 

 against the disease, as this treatment would, iu all probability free the 

 graius from auy adhering spores. 



Many fungi have a limited period of growth, or develop only at cer- 

 tain seasons of the year. A knowledge of their habits in this respect 

 may be taken advantage of iu guarding against or avoiding certain plaut 

 diseases. Early planting may secure a crop against the ravages of a 

 late growing fungus, while the attacks of an early fungus may be avoided 

 by pursuing an opposite course. 



It has been discovered that, in the round of their existence, many of 

 the injurious fungi require the support of widely-different species oi 

 plants. In one of their stages of development they may infest some 

 valuable plant, while in another, or '' alternate" condition, their home 

 uuiy be upon some worthless weed. 



A parasitic fungus, of the genus BcesteUa, which produces prominent 

 scurf3- bunches upon the under surface of the leaves of apple trees, en- 

 tirely destroying the foliage when abundant, has its " alternate" form 

 upon the common red cedar in the so-called '• cedar apples.'' The spores 

 of the form growing on the apple leaves will uot germinate except they 



• Peck, 34th Rept. X, Y. State Mus. Nat, Hist., p. 27. See, also, Bessey in Bulletin 

 Iowa Agr. College, 1884. 

 t Rept. Wis. Agri. Exper. Station, 1883. 



