Travel can be enlightening. In Turkey I learned that sour orange rootstock is routinely used with lemon and mandarin scions without any fear of tristeza virus, a formidable disease of oranges. When I heard this I asked Georgios Vidalakis in charge of the UC Clonal Protection Program and a virologist. And he said that it was true and the neat thing is that the rootstock can handle heavy, calcareous soils better than other citrus rootstocks. So we are doing a trial on rootstocks and sour orange is included.
Something else I “learned” was that if you girdle citrus at flowering, the fruit has few or no seeds. Well, I talked to many growers and scientists and they all said the same thing. I went through the citrus literature and I could find no mention of this. I emailed Carol Lovatt, the plant physiologist at UCR and she said that when you alter hormone flows by girdling, who knows what might happen. So we set up a little trial in lemon that flowers pretty much all year long on the coast. Every month we girdle branches with either a hand saw or a girdling knife which make different sized cuts, flagging the branches with different colored tape to identify the girdling date. Over an 18 month period we harvested fruit and cut it to count seeds. And………………………………………there was only a slight difference in seed numbers, a few less in the girdled trees.
The goal of this trial was to see if girdling worked and if so, what was being changed in the tree and if could identify that, then maybe we could develop a nutritional program that would do the same thing. That way we wouldn’t need to girdle. But not everything you hear turns out to be true.
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