EFFECTS OF FREEZES ON CITRUS IN CALIFORNIA 281 



a time when lemons were not paying. There are also some places 

 where trees with lemon tops have orange trunks. 



Several places were found where young trees with lemon tops and 

 orange trunks were set among lemon trees of the same age which had 

 lemon trunks. In one of these places the trees were all of the same 

 age, having been set about one year. Most of the trees had lemon 

 trunks, but there were two rows of trees in the middle of the grove 

 that had Valencia trunks with lemon tops. The trees of the grove 

 were uniform in size, and previous to the freeze there was nothing 

 to draw one's attention to the fact that some of the trees in this young 

 lemon grove had orange trunks. After the freeze, however, any one 

 passing this grove would have noticed that two rows in it differed 

 in some important respect from the rest of the trees. For the trees 

 with orange trunks bore branches covered with green leaves, live 

 lemon branches and lemon leaves, but the other trees in the grove 

 were killed nearly or quite to the ground. Four other places were 

 found where young lemon trees with orange trunks were adjacent to 

 young lemon trees on their own trunks, and in all of these cases the 

 trees with the orange trunks proved much hardier. It might be 

 thought from this that the superior hardiness of the trees with orange 

 trunks is due to the well known greater resistance to freezing which 

 orange wood possesses. It is rather hard to see on this basis, however, 

 why the lemon tops of the trees with the orange trunks should have 

 been so slightly injured. The superior resistance of the trees was 

 not confined to the trunks, for their lemon tops were hardier than 

 the tops of the trees with lemon trunks. It is clear that the trunks 

 of these trees had influenced the tops and had increased their hardi- 

 ness. This probably means that in some way the trunks of the trees 

 modified the dormancy of the tops. 



Not many bearing groves have been worked over from oranges to 

 lemons, so that it has not been possible to find many comparisons 

 between such groves and bearing lemon trees on their own trunks. 

 Some bearing lemon trees with orange trunks were found, and also 

 some bearing lemons which had tangerine trunks, but these trees did 

 not seem to be strikingly hardier than ordinary lemon trees. 



It was much easier to find bearing orange groves where the trees 

 in parts of the grove had lemon trunks. Such groves are rather 

 common in southern California because about ten years ago there 

 was such a depression in the lemon market that many growers budded 

 their lemon trees over to oranges. 



In some places these orange trees with lemon trunks were injured 

 much more than adjacent orange trees on their own trunks. One 



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