Ren.(Dityl. )iZ 



Tlie same approach to the problem had been done already in "-weden by 

 Binp;efors. He found from bis work that inoculation of ooedlinf^s in 

 the laboratory was the only possibility of making fast progress in 

 tlie breeding program. The first to develop a good method for labora- 

 tory inoculation of plants was Bingefors. His technioue is to olace 

 seeds or seedlings along the edge of a long strip of filter pa[)^^r. 

 Over this strip is laid a second sheet of filter paper . Both sheets 

 of filter paper are moistened; the seeds then will stick to the papf-r. 

 The sheets are rolled up together and the roll stood on md in a beakni 

 with some water in the bottom. The edge of the roll with the seeds is 

 uppermost. 



In two or three days the seeds will germinate. As soon as they start 

 germinating they are inoculated either by putting a nematode suspension 

 on top of the whole roll of paper or by putting a drop vrith a certain 

 number of stem nematodes on top of each germinating seedling. After 

 three or four days the first symptoms will appear, or a little l(m-';pr 

 time can be allowed. 



In about four days the paper is taken out of the beaker and unrolled. 

 One of the papers is folded back and the plants are examined. Tl'e 

 infected onesare discarded, keeping only those free of disease. The 

 paper is folded back, rolled again, and replaced in the beaker for a 

 week or so and tlien rechecked. 



It is really a very handy method. In about two weeks one can select 

 the resistant plants, take them from the paper, and plant tlien in ooiJ. 

 In this way one can inoculate and investigate thousands of secdlini'o in 

 a very limited space, and, m-oreover, one can keep the seedlings at the 

 same temperature winter and summer. This is about 10*-' to 15'^^ C. There 

 is usually no objection, as far as the observation of the infestation 

 of the plant goes, to using a higher temperattire, but generally more 

 molds and bacteria develope on the paper. So it is better to keep the 

 temperature rather low. 



In Holland, we were rather interested in having a similar kind of 

 laboratory test for rye plants. However, the rye seed is ton thick 

 to be rolled between thin sheets of filter paper. We finally devf>lop«d 

 a method that solved the problem. We used a rectangular shaped filter 

 paper pad that is hmm thick. We cut slits in the filter paper, using a 

 sharp chisel, and the seeds were inserted in the slits. The paper was 

 then mositened a little, but not too much as it becomes too soft. l(y<^ 

 seed has a sharp point at tlie end where the embryo is situated. The 

 seeds are pushed into the paper with the sharp point forward, using n 

 pair of forceps with grooves in the tips . The filter paper 



pads are supported in an aluminum frame, and these can be stood one 

 next to another in a box. 



To make the inoculation of the red clover, when used in this tecl'rii()nr 

 ir in some other way, we simply take a drop of nematode suspension ("on- 

 t lining about ten stem nematodes and place that drop on the plant. X'or 



