May, ip20 



BETTER FRUIT 



Page 9 



Control of Insect Pests and Fungous 

 Diseases. 



Only incidental reference to insect 

 pests and fungous diseases is consistent 

 in the present connection. This refer- 

 ence is made primarily to call attention 

 to the place which the control of in- 

 sects and diseases hold in the success- 

 ful management of a peach orchard 

 and to indicate the sources of help and 

 information which are available to 

 peach growers. 



After a grower has pruned intelli- 

 gently, tilled and fertilized his orchard 

 well, and irrigated it if it has been re- 

 quired, the orchard may be short lived 

 and the crops financial failures if he 

 neglects to give proper attention to the 

 control of the insects and diseases 

 which habitually occur in his region. 

 AMiile it is true that there are some 

 rather serious peach parasites which 

 are regional in their occurrence and 

 some of those which are widely dis- 

 seminated remain unknown thus far in 

 certain districts, it is likewise true that 

 a considerable number of both insect 

 pests and fungous diseases are to be 

 found pretty nearly everywhere in the 

 country in which peaches are grown. 



Every fruit grower should be in close 

 touch with the agricultural experiment 

 station in his state, so that he can refer 

 emergency matters there without delay. 

 Not infrequently, the securing of infor- 

 mation regarding the control of some 

 insect pest that has become suddenly 

 threatening or concerning the most ef- 

 fective means of checking the spread 

 of a disease hitherto unknown results 

 in saving what would otherwise have 

 been a serious loss. 



Inquiries relating to any phase of 

 fruit growing may also be referred at 

 any time to the United States Depart- 

 ment of Agriculture, where without 

 cost, through the department's patho- 

 logical, entomological and other experts 

 as full information relative to the prob- 

 lems as can be given may be secured. 



Interplanted Crops. 



The growing of some annual crop 

 between the trees during the first two 

 or three seasons following the planting 

 of an orchard, as an aid in meeting the 

 maintenance cost during the unproduct- 

 ive age of the trees, is frequently an 

 economic expediency. This practice, is 

 seldom, if ever, any advantage to the 

 trees in comparison with thorough till- 

 age by itself, but if interplanted crops 

 are wisely selected and properly man- 

 aged with respect to their relation to 

 the trees, they are not likely to result 

 in any serious harm. 



The interplanted crop ought to be one 

 which needs essentially the same tillage 

 that the peach trees should have. Where 

 this is the case, the secondary crop 

 does not seriously interfere with that 

 operation. But the grower should real- 

 ize that he is in effect, following a sys- 

 tem of double cropping and that be- 

 cause of the interplanted crop he may 

 need to give more attention to the main- 

 tenance of the fertility of the soil than 

 he would for the peaches alone. After 

 the trees reach bearing age, they should 

 not be made to compete with another 

 crop. Even if there is sufficient plant 



food in the soil to produce successfully 

 two crops at the same time, the peach 

 tree will usually need all of the avail- 

 able soil moisture, except, of course, in 

 sections where irrigation is practiced 

 and there is an adequate supply of wa- 

 ter for all purposes. Besides, an inter- 

 planted crop would be likely to inter- 

 fere with the spraying of the trees, if 

 that operation should be necessary, 

 with the harvesting of the fruit, and in 

 other ways. 



Provided interplanted crops do not 

 interfere with any of the operations re- 

 quired in the proper development of 

 the trees, a considerable range of choice 

 may be exercised by the grower as to 

 what he shall use. The selection may 

 be governed to some extent by the rela- 

 tive market value of different crops 

 that can be grown in different regions. 

 Muskmelons, beans, peas, cabbages and 

 tomatoes, and other truck crops are ex- 

 tensively grown in this way in different 

 sections. Potatoes are sometimes used 

 but they are suitable only when the 

 crop is so managed that the digging of 

 the potatoes will not amount to a late 

 cultivation, which may be attended with 

 undesirable results. Corn, also, is fre- 



quently used, but as very often managed 

 is objectionable, because it shades the 

 trees excessively. Whenever corn is 

 interplanted, an open strip of consider- 

 able width should be left along the 

 rows, so that the trees will be fully ex- 

 posed to the sunlight throughout the 

 season. If a very tall, strong growing 

 variety of corn is used, a wider strip 

 should be left unplanted than where a 

 dwarf variety is used. 



Peach trees are sometimes used as an 

 interplanted crop, especially where 

 apples comprise the permanent crop. 

 This practice is both highly commended 

 and emphatically condemned by fruit 

 growers of wide experience. It is prob- 

 ably objectionable in that for a number 

 of years both bearing and non-bearing 

 trees occupy the same area, and it is 

 sometimes desirable to treat a fruiting 

 tree very differently from one that is 

 not bearing, for the best results with 

 each. On the other hand, where a site 

 is particularly favorable for both 

 fruits, a compromise treatment can 

 often be effected, which yields fairly 

 satisfactory results with both kinds of 

 trees. 



Winter Injury or Die-Back of the Walnut 



By L. D. Batchelor and H. S. Reed, of the University of California, College of Agriculture 



THIS article contains an account of 

 studies made through several sea- 

 sons on the so-called "Die-Back" or 

 "Winter Injury" of the Persian walnut 

 (Juglans regia.) In certain districts 

 where walnuts are commercially grown 

 the trees have suffered greatly from 

 this trouble, and in some cases parts of 

 orchards have died from this cause. 



Unfavorable soil or climatic condi- 

 tions which would show little or no 

 effect upon many species of orchard 

 trees, may seriously injure, if not ac- 

 tually kill, a walnut tree. The effect of 

 such unfavorable conditions is often 

 first clearly manifested in the early 

 spring. At that time the tops of healthy 

 trees make rapid growth, whereas the 

 tops of injured trees show no growth 

 whatever. Frequently imfavorable 

 conditions not only cause the death of 

 the uppermost twigs but also of some 

 of the older branches. 



"Winter Injury" is a term frequently 

 applied to several conditions, the effects 

 of which are particularly evident in 

 the early spring. Usually "Winter In- 

 jury" is most clearly manifested by the 

 death of the young twigs and small 

 limbs and hence is frequently known 

 as "Die-back." These terms will be 

 considered as synonymous in the fol- 

 lowing discussion. 



Winter injury may be considered as 

 the final effect of one or more condi- 

 tions which are adverse to the normal 

 growth of walnut trees and which 

 eventually cause them to die back in 

 the tops. The following are the most 

 common causes of winter injury: (1) 

 Early autumn frosts, (2) winter 

 drought, (3) high water-table, and (4) 

 alkali soil. 



1. Early Autumn Frosts — Young trees 

 are more likely to suffer from early 

 frosts than are mature bearing trees 



because the latter go into a dormant 

 condition earlier in the season. Walnut 

 foliage which is still green and shows 

 no sign of its normal autumn color, is 

 apparently as subject to frost injury as 

 are tender vegetables. Such injured 

 foliage drops prematurely, and hence 

 the green, immature twigs are fully ex- 

 posed to the sun's heat during bright 

 days in fall and winter. The moisture 

 loss, following the dropping of the 

 leaves, is much more rapid from the 

 succulent twigs than from the more 

 mature growth. 



In many cases the twigs themselves 

 are not actually injured by the frost, 

 but are killed by sunburning following 

 the loss of the leaves. This is substan- 

 tiated by the fact that such twigs usu- 

 ally begin to show injury from sun- 

 burning about the middle of January. 

 By early spring, more or less of the 

 new growth is dead. In occasional in- 

 stances, however, a portion of the 

 north side of twigs thus injured may 

 remain healthy and produce normal 

 growth in the following spring. The 

 death of the immature twigs is due not 

 so much to the initial low temperature 

 which killed the leaves as to the subse- 

 quent sunburning of the exposed bark. 

 Vertical young shoots frequently show 

 discolorations due to sunburn on the 

 south side over their entire length, 

 while horizontal or oblique branches 

 usually show this sunburned area more 

 strikingly on their upper sides. Such 

 a sunburned appearance of the young 

 limbs in the spring is a prevailing char- 

 acteristic of trees which have been only 

 mildly frosted the previous fall before 

 the dormant period set in. Inasmuch 

 as the root systems are not injured by 

 this condition, such frosted and sun- 

 burned trees, as a general rule, produce 

 a rank, succulent twig growth the sum- 



