BETTER FRUIT 



AN ILLUSTRATED MAGAZINE PLTBLISHED MONTHLY IN THE INTEREST OF MODERN, PROGRESSIVE FRUIT GROWING AND MARKETING 



Combination Spraying for Insect Pests and Fungus 



By Paul R. Jones, Manager and Entomologist Insecticide Department, Balfour, Guthrie & Co., San Francisco 



THE busini'ss of modern fruit grow- 

 ing has become so competitive of 

 recent years tliat every jjrancli of 

 the industry is now very liighly 

 specialized. Probably no other part 

 of the fruit business has made such 

 great strides the last ten years as the 

 scientific treatment of the trees for the 

 control of insect pests and fungous 

 diseases. Not very long ago lliis phase 

 of fruit growing was very lillle under- 

 stood and most of the known insect 

 remedies were hand-picking, lime- 

 sulphur and kerosene emulsion. In 

 fact, some entomologists, who advised 

 the above remedies and no others, were 

 known as "Kerosene Entomologists." 

 With the greatly increased acreage of 

 fruits that has been set out recently, 

 and more discriminating selection by 

 buyers and consumers, it was imiiera- 

 tive that the growers themselves un- 

 derstand the contiol of the troubles 

 which destroy their crops. It is not 

 unusual now to find in any fruit section 

 numbers of fruitgrowers who are able 

 to tell intelligently how to control these 

 pests, and at the same time put their 

 methods in practice in the field. The 

 rise and increase of these difi'erent 

 insect pests and fungous diseases, due 

 to many causes, has led to the use of 

 a variety of sprays and it is of the 

 utmost importance that wherever pos- 

 sible the combination of two or more 

 materials, either for dilferent types of 

 insects or for insect pests and fungous 

 troubles, shall be made with the same 

 application, since a great part of the 

 cost of the spraying is due to the labor 

 in applying. This side of applied eco- 

 nomic entomology, as related to fruit 

 growing, is probably the most recent 

 of any, and I will now endeavor to 

 show some of the more recent, at the 

 same time older, combinations which 

 may be used in orchard - sjjraying 

 practice. 



The insect which started combina- 

 tion spraying on an extensive scale on 

 the Pacific (^oast was the Pear Thrips 

 in California. While this insect is in- 

 jurious to a number of orchard fruits, 

 it confined most of its attacks to the 

 pear, prune and cherry. The prune 

 growers and cherry growers in Cali- 

 fornia never had done much spraying 

 until the Pear Thrips came aloTig, with 

 the possible excei)tion of some winter 

 treatment such as lime sulphur or 

 c ude-oil enndsion. The pear growers 

 had been used to spraying for Codling 

 Moth, Pear Scab, Scale and several 

 minor troubles. On account of the 

 .short period in which the Pear Thri|)s 

 was able to absolutely ruin ci'ops it 

 was necessary for the grower to bend 



all his energy toward combating this 

 pest. At the same time it was desirable 

 to try and control other insect and 

 fungous troubles during this applica- 

 tion, otherwise more labor would be 

 required foi- any other spraying and a 

 heavier investment in s])raying eauij)- 

 ment, and it would not be possible to 

 put on the additional applications for 

 these other insect pests and fungous 

 diseases in time to control them i)rop- 

 erly. The early investigations for Pear 

 Thrips control were worked out on 

 separate lines of oil emulsions and 

 nicotine compounds, but it was found 

 that the nicotine comijounds did not 

 have the required penetration into the 

 fruit buds by themselves, and that the 

 oil emulsions when used at a sullicient 

 killing strength by themselves were 

 liable to cause injury. Hence, the com- 

 bination of the two was formeil. After 

 the petals had fallen it was necessary 

 to spray for the Codling Moth, and 

 arsenate of lead was added to this mix- 

 ture. One orchard in Santa Clara 

 County was also sprayed for Pear Scab 

 and had the addition of bordeaux mix- 

 ture to the above conibinal'on. A report 

 on this orchard showed later that no 

 injury to the foliage was acconii)lished, 

 practically no worms were jjresent, 

 the crop was saved from the attacks of 

 the Pear Thrips and no Pear Scab ap- 

 peared. This orchard was treated sev- 

 eral times with the above combination 

 of the four dilferent materials. 



The last year or so fruitgrowers on 

 the Sacramento River, where the Pear 

 Thrips is (piite prevalent, have been 

 using on pears a coi'ibination of 

 miscible oil, Black Leaf -JO, arsenate of 

 lead and atomic sulnhur, all in the 

 same tank, and obtain perfect results 

 with each material for the ])urpose for 

 which it was intended. On i)runes and 

 plums the arsenate of lead is left out 

 unless the orchard is infested with 

 Canker Worms. It might be well to 

 add here that the miscible oil and 

 Black Leaf 40, or oil emulsions and 

 Black Leaf 40, have given very good 

 control of the Canker Worms in the 

 Santa Clara Valley and elsewhere just 

 after they have hatched from the eggs 

 and at the regidar time for the Pear 

 Thrips api)lication. In case this api)li- 

 cation is |)ul on rather late it is de- 

 sirable to aild arsenate of lea<l to the 

 above mixture to catch any straggling 

 Canker Worms that may show up. It 

 is often possible in this way to get 

 around using a large amount of arse- 

 nate of lead on plum and prune, the 

 foliage of which is ver\- susceptible to 

 iniui> by this poison. The al)ove com- 

 bination has also controlled the Prune 



Aphis when applied just after the petals 

 have fallen, presumably killing the 

 stem mothers, while applications for 

 the adult thrips was of no avail against 

 this aphis. Still further, in comment- 

 ing on this combination in spraying 

 prunes, where no Canker Worms or 

 fungus was present, the arsenate of 

 lead and the atomic sulphur were omit- 

 ted, and it was noticed after the two 

 or three Pear Thrips a|)plicalions that 

 the Brown Apricot Scale was con- 

 trolled very well for the year, show- 

 ing here the accunudative benefit of 

 weak-oil emulsions. It might be well 

 to add here that in this (innbination of 

 oil emulsions Black Leaf -10 and arse- 

 nate of lead, usually no trouble is expe- 

 rienced out in the field, except where 

 very hard water is encountered. Cer- 

 tain sections of Califoinia have such 

 notoriously hard water that it is neces- 

 sary to clean out the si)ray tank after 

 each load and also use some water 

 softenei' or an excess of soa]) with the 

 oil emulsion. Repeated experiments 

 last year showed that where a stand- 

 ard oil enndsion was diluted to a cer- 

 tain strength and Black Leaf •!() added 

 at the regular thrips strength, and also 

 Xicofume 10 added at the same strength 

 in another test tube of diluted emul- 

 sion, that the Black Leaf 40 broke down 

 the oil emulsion quite rapidly (this is 

 to say, within a day or so), while the 

 Nicofume 40 in condiinalion with the 

 dilute enndsion remained in solution 

 indefinitely without the slightest bit of 

 separation. The Black Leaf 40 evi- 

 dently has more of an acid reaction 

 than the Xicofume 40, which is sup- 

 ])osed to be free nicotine, hence in very 

 hard water the former will break down 

 oil enuilsions. especially if they do not 

 contain a little more emulsificr than is 

 absolutely necessary. 



Other combinations that a'c used in 

 California are crude-oil enuilsions and 

 caustic soda, or distillate-oil emulsion 

 and the latter, for clean-up work in 

 the winter on Scale or Moss and 

 Lichens. The writer iiersonally does 

 not like to recommend a very high 

 amount of caustic soda for two rea- 

 sons: it is apt to break down the ennd- 

 sions and has a habit of h.ardening the 

 bai'k and killing the fruit buds. Even 

 stiiuig alkali-soap solutions ad<led to 

 oil enndsidus contain so nuich caustic 

 that Ihev will eitlier increase the pene- 

 tration (if Ihe oil emulsion to such an 

 extent that either one or both will 

 destroy a large jiercentage of fruit 

 buds. This was especiallx' noticed last 

 \ear in a pear orchard where a strong 

 laundry soap w-as used with home- 

 made dislillale-oil enndsion, in com- 



