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1917 ANNUAL REPORT 



suits on any soil with a tight compact subsoil or in adobe land. The only 

 place it is possible is on well drained sandy soil or side hills of light soil. 

 The avocado will not thrive in soggy land even if this condition lasts only 

 a few months, 



J. T. Whedon: The subsoil is very important. The subsoil in my 

 grove in Yorba Linda is heavy clay, the first foot being a sandy loam with 

 the next five feet a heavy clay loam with more or less sand. Last Janu- 

 ary, a year ago, there were almost continuous rains. I lost nine large Har- 

 mans on account of poor drainage. The avocado will not stand poor drain- 

 age, but with good drainage it is a difficult matter to give them too much 

 water. 



Dr. Keller: Part of my soil is sandy silt to about 8 feet. The hill- 

 side is black loam with disintegrated granite and clay subsoil. The subsoil 

 does not take water very well, although the surface takes it readily. 



E. E. Knight: For the first two years there is no doubt but that the 

 drip system is the best, as the water is needed close to the tree, also less 

 water is used than under any other mode of irrigation. But as the roots 

 extend farther, it is more difficult to distribute the water properly. Also in 

 most drip systems the stand is placed too close to the trunk of the tree. It 

 is soon covered by the branches and difficult to get at. If an orchard is 

 to be piped along each row, the stand should be placed in the center be- 

 tween each four trees ; from there the water should be conveyed with either 

 a short piece of pipe or by some other means to the trees while they are 

 still small. The stand is in this case, always easily reached, and should 

 an overhead system be installed later, the stands will be in their proper place. 

 By placing a bean straw mulch under the trees, not only can much water 

 be saved but at the same time the soil can be enriched. 



The only sure way to know when to apply water to the trees, is to 

 test the soil for humidity ; but this is quite a task, so I lift up the mulch and 

 if the fish worms are working I know the soil is still in good condition. As 

 soon as the worms seem to be laying off, I fill the basin once; never soak 

 the soil. I irrigate every week or ten days during the warm weather but 

 use less water per month than is used on citrus. The amount of water used 

 and frequency of irrigations depends on the class of soil. Most any system 

 will keep an avocado tree alive and growing, but what we all wish to know 

 is which system gives the best results. 



C. F. Booth: Before giving my experience in irrigation I will say that 

 my soil is different from most others in which avocado trees are grown. It 

 is a sandy loam on top but becomes a sandy clay loam below. The soil 

 is not deep being only 3 to 6 feet to bed rock. Last year I irrigated about 

 every thirty days, using the basin system around the trees, with no ill effects. 



This year having a much hotter summer, I irrigated every two weeks. 

 The trees got along nicely until about September 1 , when a large number 

 of them — 40 or 50 perhaps — developed what I have reason to believe is 

 called black spot. Last year some children left a water hydrant running 

 and flooded the basin around a young Lyon tree. The water must have 

 been running three or four days before I discovered it. Some ten days or 

 two weeks after that, a prominent Eastern nurseryman of wide experience, 

 while looking over my place, noticed the Lyon tree and drew my attention 

 to the leaves. They were spotted in the body of the leaf with purplish 



