Arizona republican., 1902-03-16
IA MEETING 0F
 ORANGE GROWERS
Discussion of a Subject Of
 Vital Importance.
Investigations of Prof. R. H. Forbes Concerning Recently Developed Problem in Citrus Tree Culture.

For the last three years the orange | growers of the valley have been some- what perpleXed by the dying back of the tender outer twigs on their trees. There seemed to be no explanation of the cause, which is of course necessary to determine previous to finding a rem | edy. Prof. R. H. Forbes of the terri | torial university was requested to take | up the subject and for several weeks | past he has been carrying on his in vestigat tions visiting the orchards of the valley a various times. Yesterday afternoon most of the orange growers gathered in the board of trade room and listened to a very interesting ad- Gress by Prof. Forbes, setting forth the result of his investigations, and also comparing notes with each other on their personal observations.
 Prof. Forbes said he found that the system of shallow irrigation prevailing in most of the orchards had resulted in developing the root systems of the trees close to the surface. In many cases the feeding roots of the trees
 were found in great number within six
 ltiCIlSS u IOOl pL liiS oui IdNG. IT
 dry time this position of the roots
 naturally subjects them to extreme drouth.
 The soil conditions were examined
 with reference ta alkali. a majority of the orchards being examined to a depth Of from four to eight feet. It was found that though the virgin soils of the upper slopes of the Salt river valley are nearly free from alkali, consider able quantities of deleterious salts had
 accumulated in the soils of affected or chards. According to numerous anal yses made by the experiment station it | is known that the water of Salt river during the hot, dry weather of the last
 two summers especially, has contained an abnormal percentage of salts which | in course of irrigation have been ap- l piled to the orchards, thus accounting ] for the presence of large quantities oi 1 alkali observed in many instances. I;
 was found moreover that these salts ! in many cases had accumulated near l the surface in contact with the tree roots. also brought to the surface l through shallow irrigation.
 Although it is possible that climatic 1 influences may also be partly resp.ns-
 ible for the difficulty. the presence of such accumulations of salts in the soil 1 indicates q very probable cause of the 1 trouble. The remedy must consist in such a system Of culture as shall mit- gate the effects of alkali on the trees, | lead to a deeper establishment of root
 systems, and distribute the alkali through the soil in such maner that 1 its harmful effects will be reduced. l. i was observed that in the Dr. Hardy or
 chard, which for the last two years has
 been in alfalfa and has been flooded in ! consequence, the alkali had been dis
 tributed through the upper six feet in Nsuch a manner that it was nowhere | concentrated in injurious quantity. l.
 was suggested that when possible the
 occasional flood waters available
 should be used for washing the accum-
 ulated salts into the lower soil and pre-
 venting their return to the surface by
 deep and thorough cultivation.
 | In the discussion following the re-
 marks submitted it was stated that
 several growers of the valley are using
 subsoilers for the purpose of getting
 the water supply deeply into the
 ground. This device, much in use in i California, if employed. should lead to deeper root systems. The surface roots 1 being broken by the subsoiler are com pelled to reeStablish themselves further
 down.
 MT. Young reported his interesting re-
 suits in shading trees. In a prelimin-
 ary experiment made in shading d small number of trees last summer, 1 the foliage was kept green and healthy
 and he is following up the work by
 shading a considerable area this year. | Samples of foliage were shown by MT. | Young, some from the shaded places
 and some from exposed trees. showing
 that the shaded foliage had strong
 green color while the foliage from the ! exposed trees was considerably | bleached.
 It is by no means certain, it would seem. that alkali is the only offender in connection with the present difficulty 1 but there is little doubt that the syS- ! tenn of shallow irrigation at present in
 vogue may be improved upon and the
 situa tion is one requiring prompt action. Although MT. Young's experiment ir- dicates that climatic influences have | conspicuous effect upon the foliage, yet | It IS quite possible the weakened con- clifton of the trees brought about by | the presence of alllali in the soil may | increase the effects of an excessively 1 hot, dry climate. On the basis of ob-
 served facts experiments are being ir- ley with reference to the exact cause of | the difficulty.