350 



A NEEDED EXPERIMENT. 



not attack a healthy potato plant. It was also true that 

 Pliytophtliora oninivora, though growing on a variety of 

 plants, will not attack the potato. Fig. 4 shows part of 

 the mycelium and two oospores of Pythium vcxaiis, Fig. 

 5 is an oospore germinating by the formation of zo- 

 ospores. Fig. 6 shows a similar spore germinating by 

 forming a tube. Either process may occur. 



With regard to Pvt/iiitin DeBaryaniim, DeBar)- says : 

 "This pythium is, as Hesse has shown, a dangerous 

 parasite. It is disseminated in garden soil to a remark- 

 able degree. Therefore, one may be easily convinced 

 that it almost always seizes upon plants subject to its 

 attacks when they are sown in such earth and kept wet. 

 One can be quite sure of obtaining the fungus by this 

 means for examination at any time. The fungus may 

 perhaps lie dormant in the earth in the form of myce- 

 lium, which it does at any rate in the form of resting 

 conidia and oospores, which may retain their vitality 

 through months of dryness. From the plant first attack- 

 ed the mycelium spreads over the moist earth and then 

 attacks the neighboring stock. The injury and death of 



seedling phsenogamous plants sown in wet places have 

 in this, as Hesse has shown, almost always their imme- 

 diate cause. " 



This species, then, is the one which will most likely 

 prove to be the cause of damping-off in America. Fig. 

 7 contains an unripe oospore. Fig. 8 is one that has 

 germinated. 



Recent culture of the fungus which I have made con- 

 firms the supposition that damping-off is caused by 

 fungi. 



The figures are all from DeBary. Figures 1-3 repre- 

 sents various parts of PJiyloplitliora or PytJiium omnivora: 

 I, conidia (xgo); 2, germination of zoospores (X225); 3, 

 a ripe oospore with remains of antheridium (X375). 

 Figures 4-6 show Pylhiiitii vc.xatis : 4, mycelium and 

 oogonia (x6oo); 5, oospore germinating by formation of 

 zoospores (X300); 6, oospore germinating by formation 

 of a tube (X300), Figures 7 and 8 are Pythiittn DeBary- 

 aiiHiii: 7, oogonium containing unripe oospore, anther- 

 idium attached (X375); 8, germinating oospore (X250). 



A NEEDED EXPERIMENT." 



After reading the article, " Some Literature," in 

 the January number of The American Garden, in 

 which the author presumes upon a wide acquain- 

 tance with experiment station Hterature, it is some- 

 what surprising to hear from tlie same source, un- 

 der the heading "A Needed Experiment," in the 

 February issue, that the question " how shall we cut 

 our potatoes for seed," is "new and vital to the 

 potato." True, it is vital to the potato grower, 

 but it is very far from being "new" or a question 

 that "has not already occupied the attention of 

 scientists." There has been more than one man 

 who, according to the writer of that article, is en- 

 titled to " be * * * * considered a benefac- 

 tor of his race." Few subjects have received more 

 attention from experimenters. 



For at least one hundred years, investigators have 

 been studying this question, and to-day the general tes- 

 timony of experimental research is the same as when, in 

 1807, Mr. Dickson in his great work on agriculture^ 

 wrote: "It seems probable from the various experi- 

 ments that have been made upon the subject, that the 

 middle-sized whole potatoes, and the cuttings of large 

 ones, are, in general, more productive than either the 

 smaller sort of whole potatoes, small cuttings, or the 

 eyes or shoots alone." In support of this statement Mr. 

 Dickson gives tables showing the results of experiments 

 carried on yearly from 1790 to 1795 (excepting 1793). 



Long before experiment stations were established in 

 this, or any other country, this subject had received 

 attention, and we have omly to examine the reports o^ 

 the U. S. Department of Agriculture, beginning with 

 the isBue of 1847 from the Patent Office, to find that it 



has for many years been a live question among potato 

 growers. 



Referring simply to work on this subject at the expe- 

 riment stations of this country, we can point to the 

 records of more than thirty distinct trials, published in 

 their reports and bulletins. 



Many foreign publications, as weW as the columns of 

 our own agricultural papers, contain also the records of 

 work in this line, performed by both public and private 

 experiments. 



It is now a well established fact, that, speaking in gen- 

 eral terms, "the larger the amount of seed potato 

 planted, the greater the corresponding crop. " This does 

 not mean that the crop is proportional to the seed plant- 

 ed, but simply that it increases to a certain extent as the 

 amount of seed is made larger. When very large quan- 

 tities of seed (forty to sixty bushels per acre) are plant- 

 ed, the increase is oftentimes not enough larger to pay 

 for the increased cost of the seed. 'J'lie most profitable 

 amount of seed to plant is the medium ; that is a ivhole 

 potato or a piece zveighiug three or four ounces and con- 

 tuining from two to four or five eyes. Experiments al- 

 most universally show that it is never safe to trust to a 

 piece with only a single eye, per hill. 



The above conclusions have been reached after care- 

 ful study of all available records, and it will be seen 

 that the principal one, regarding the proper amount of 

 seed to plant, is not diflerent from that recorded nearly 

 a century ago. Several experiment stations are, at pre. 

 sent, at work on the subject, and further data are con- 

 tinually being added to that already at hand. 



Maryland Experiment Station. W. H. Bishop. 



[We did not suppose it to be necessary to explain that 

 R, T. Choke was writing in sarcastic vein ! — Ed. Am.G.] 



