THE TESTING OF A NEW TREE 



CROP FOR HARDINESS 



David 1-\\ikchii,I) 



Agricitlfitral lixplorcr in Cluiryc of Forciyu Seed and Plant Introduction. I'. S. 

 Department of .lyricnltnre, ll'asliini/to)!. P. C. 



IX A REGION like that of the Gulf 

 States where there is a great range 

 in the minimum temperature from 



year to year, it is not a simple thing 

 to determine whether a tree crop of 

 some new introduction can be grown 

 there or not. There are so many factors 

 and tiiey are so complicated and their 

 solution runs away with so much of an 

 investigator's life that it is almost a 

 discouraging Imsiness to attem])t to test 

 out a new tree crop in a new region. 

 It must l)e done though, and in the do- 

 ing of it, those of us whose business it 

 has been to do this kind of work are 

 learning a few things which it seems to 

 the writer are worthy of recording for 

 the next generation of experiiiienters. 

 This brief note is intended to cover 

 only one feature of the dif^culty which 

 attends this kind of work, viz., that 

 which has to do with the protection of 

 the young plants through their baby- 

 hood and at the critical times when in 

 our Gulf States in particular every new 

 tree runs the supreme danger of death 

 from freezing. 



Young trees like young people are 

 more tender than the grownups and the 

 little baby trees, which, when they are 

 fully grown will weather severe freezes, 

 are often killed outright by light frosts 

 and never get a chance to prove their 

 ability to stand the cold. 



Through a series of years those of 

 us in the Oflice of Plant Introduction 

 who are interested in the problem have 

 been watching some experiments in the 

 acclimatization in Northwestern F'lor- 

 ida of the hardier or Mexican type <»f 

 avocado. 



One of our field stations is locatid 



at lirooksville. in that remarkable ham- 

 mock region of Western Florida where 

 the .soil conditions appear to be favor- 

 able for the growth of the avocado and 

 it was at this station that the tests were 

 made. The climate of Brooksville dur- 

 ing all but a very brief period is of a 

 character favorable to the growth of 

 this tree, but there are short periods, 

 usually in the month of February, when 

 for a few nights the thermometer drops, 

 if there is no wind, to even as low as 

 18° F. 'J"he temperature does not 

 remain there for more than a few 

 hours, but long enough to devastate 

 a garden of tropical plants so com- 

 pletely as to discourage any but the 

 real pioneer in plant introduction. It 

 is a strange experience to wander 

 through a garden upon which one has 

 spent years of thought and labor and 

 to find that during a few hours just be- 

 fore dawn the pets which were so prom- 

 ising and appeared in perfect health, 

 have wilted and are actually dying be- 

 fore your eyes. This is the experience 

 of the pioneer in plant introduction. 



I remember in 1898 visiting West 

 Palm P)each where my former professor 

 of horticulture. Prof. E. Gale, had gone 

 in the eighties to study the tropical 

 mango during the last years of his life. 

 He took me out into his little garden 

 and showed me there the original Mul- 

 goba mango tree which had been killed 

 (lown to the ground on two occasions 

 but which was at that time ten feet 

 high, branching at the ground as all 

 trees do whicli are cut back by the 

 frost. 1 could not then fully appreciate 

 Professor Gale's confidence in the fu- 

 ture of the mango at Palm Peach and 



