270 ANNUAL, EEPOKTS OF DEPARTMENT OF AGRICULTURE. 



records. Up to June 1, 1923, this department had sold to propaga- 

 tors a total of 2,300,000 buds at an average price of about 5 cents 

 each. These buds have been taken from the most productive and 

 desirable citrus trees in orchards where individual tree-performance 

 records have been made for a period of several years. The trees 

 used as sources of supply were selected on the basis of these records, 

 and budwood was cut only from those trees which have consistently 

 borne high yields of uniformly good fruits. During the past year 

 it has been possible to procure part of this supply of selected bud- 

 wood from the best trees of superior progenies which were originally 

 propagated from the most productive and desirable parent trees. 



The furrow -manure method of applying fertilizers. — Additional 

 evidence has been secured during the past year as to the superior 

 efficiency and economy of the furrow-manure method of applying^ 

 fertilizers, particularly barnyard manure or similar organic mate- 

 rials, in citrus orchards in California. With the use of this method,, 

 which was originated and developed in the course of these investiga- 

 tions, the plowsole condition present in many irrigated citrus or- 

 chards is broken up and the manures applied in the feeding-root 

 zone with a minimum loss of plant food and a maximum return for 

 the fertilization. 



Stem-end rot. — It has been determined experimentally that the 

 timely removal of the attached stems, or " buttons," from citrus fruits 

 potentially infected with either type of stem-end rot will prevent 

 their decay, provided this removal can be accomplished without in- 

 jury to the fruit tissues that would give entrance to blue-mold in- 

 fection. This can be done effectively and inexpensively by an 

 adaptation of the gassing method for hastening the coloring of the 

 fruit, subjecting the fruit to gases from the exhaust of an internal- 

 combustion engine or from a kerosene stove adjusted to give incom- 

 plete combustion. It has also been found that spray applications 

 of Bordeaux-oil emulsion timed for the control of melanose will also 

 greatly reduce losses from the Phomopsis type of stem-end rot,^ 

 though they will not have much, if any, effect on the Diplodia stem- 

 end rot. 



Grapefruit storage. — The experimental work on grapefruit storage 

 has been completed, and it is now established on a commercial basis. 

 Two cars of grapefruit were cured and stored during the season. 

 With the first car, which was stored in January and removed from 

 storage in March, there was practically no rot and not enough pit- 

 ting to injure the sale of the fruit. With the second car, which was 

 stored in April and sold during the summer, the pitting was negli- 

 gible, and the percentage of rot did not increase in two months of 

 storage. A method of curing was worked out whereby the fruit 

 could be cured in three days by exposing it to the gas from kerosene- 

 stoves, removing the buttons at the same time. This treatment not 

 only prevents pitting but also eliminates much of the loss which 

 might occur from stem-end rot. The work on coloring citrus fruits 

 in Florida by employing incomplete combustion of petroleum prod- 

 ucts, such as kerosene or gasoline, was continued throughout the sea- 

 son of 1922-23. As noted above, the adaptability of these methods for 

 removing buttons from fruit in order to prevent losses from stem- 

 end rot has been determined, but imder some conditions it is ad- 



