The Garden Magazine, November, 1921 



153 



replacing b\' good trees. According to Shamel, buds and cions 

 taken from high producing citrus trees will grow into high pro- 

 ducing trees even when top worked on to trees that formerly had 

 given low vields. Just how far these results can apply to decid- 

 uous fruits generally is still an open question, but in view of the 

 known facts concerning citrus trees it is desirable that all bud 

 and cion wood for the propagation of deciduous fruits be taken 

 from trees known to be high producers. There can be no loss, 

 and possibly much advantage from so doing, and nurserymen 

 especially should bear this in mind. 



Here are some illustrative data of trees in one citrus 

 orchard : 



Average output of Tree No. 2 for three seasons . . . .768 pounds 

 " " " " 4 " *' ••••443 



Difference 3 2 5 



Value of the product at 2 cents per pound, No. 2 $15-36 



No. 4 8.86 



Difference S5.50 



The annual expense per tree in another orchard was deter- 

 mined to be S2.25. This means that when the fruit sold at if 

 cents per pound (as in fact it did), all trees yielding less than 

 1 30 pounds were maintained at a loss. The net income from 

 this grove of 1 ,525 trees was $772.56. The records showed that 

 there were 490 trees which produced no profit. By cutting out 

 those trees the profit from the remaining 1,035 trees would have 

 been Si, 125.95 or Si. 09 as against 51 cents per tree. Such 

 reasoning may be applied equally to trees in the non-commercial 

 orchard where "drones" are frequent. 



Practical directions for taking and using individual tree 

 records are given in Farmer's Bulletin 

 No. 794 of the U. S. Department of 

 Agriculture. 



Increased Production by Means of 

 Hybrid Vigor 



HYBRID vigor, as was explained in 

 the preceding article (September 

 Garden Magazine), relates specifically 

 to the increase in growth, productive- 

 ness, hardiness, and disease resistance 

 over that of the parents which often 

 results from crossing two strains, 

 varieties, or even species. This increase 

 of vigor is greatest in the first generation 

 of the hybrid and, if reproduced by 

 seed, the plants lose a part of this vigor 

 in each of the succeeding generations 

 after the first. This principle of hybrid 

 vigor, though long known to scientists 

 and horticulturists, has seldom been 

 directly considered in experiments de- 

 signed to increase crop production. Vet 

 unconsciously it has been utilized to a 

 certain extent since many of our bush 

 and tree fruits are first generation 

 hybrids that have been propagated by 

 cions, buds, runners, or rootstocks; and 

 originally selected partly because of 

 the increase in vigor and production 

 which they showed. This has figured 

 largely in the improvement in pro- 

 duction secured by Luther Burbank. 

 Also it is the reason that some of our 

 fruits fail to come true from seed. 

 In the seedlings which are not like their 

 parent we see the Mendelian segrega- 



tion of the characters carried in a latent condition in the 

 hybrid. It often happens that among these seedlings there may 

 be one or more that exhibit desirable qualities or combination 

 of the parental characters. 



In regard to hybrid vigor in Apples the New York Agricul- 

 tural Experiment Station at Geneva reports that "the hybrid 

 vigor expected of a first generation hybrid is found to a marked 

 degree." Burbank's Royal Walnut, recommended for shade 

 and forest tree plantings, and to some extent used as a root 

 stock on which the buds of the commercial English Walnut 

 are grown, is a splendid illustration of the utility of hybrid vigor. 

 It is a first generation hybrid between the California Black Wal- 

 nut (Juglans californica) and the Eastern Black Walnut (J. 

 nigra.) [A splendid every-day illustration of hybrid vigor is seen 

 in the Carolina Poplar, according to Dr. Henry, a hybrid of the 

 Lombardy and pregenerata and much more vigorous growing 

 than either of them. Dr. Henry considers the original tree "the 

 most wonderful tree in Europe in point of vigor." — Editor.] 

 The New Jerse,y Agricultural Experiment Station reports that 

 marked increase in vigor is obtained in the first generation 

 hybrids of certain Peach varieties. 



The greatest practical utility of this phenomenon to the de- 

 ciduous fruit grower lies in the use of these vigorous growing, 

 hardy, disease resistant trees for stocks on which to bud stand- 

 ard varieties of fruits. The advantages of such stocks to the 

 nurseryman and fruit propagator are only too obvious; and 

 through them the individual gardener will be reached. 



When the hybrid in addition to being more vigorous than 

 either of the parent plants also produces abundant fruit of good 

 quality it can be grown on its own roots and other trees propa- 

 gated from it by budding it on to other vigorous first genera- 

 tion seedlings. Since one or both of the parents may them- 

 selves be hybrid, not all the first generation plants from a cross 



A PROGRESSIVE STEP IN STRAWBERRY MAKING, THE TREBLA 



A remarkable hybrid produced by a combination of nine different ancestors. Notice 

 its upright habit and the presence of ripe fruit, green fruit, and blossoms all on 

 the same plant at the same time. This illustrates the principle of "hybrid vigor" 



