-4- 



FROGRESS REPORT ON CliEMICAL THIMING TESTS 



Chemical thinning tests were conducted at Amherst rjid in three commercial 

 apple orchards using the dinitro materials (DW i^l and Elgetol) at blossom time and 

 the sodium salt of naphthalenep.cetic acid (App-L-Set) at oalyx time and two and 

 four weeks after calyx. One test on' Halehaven peaches was conducted using three 

 dinitro materials (DN #1, DN #289, and Elgetol) at blossom time. 



Although the bloom was heavy, the v/eather, except for the first t\vo or three 

 days v/hen apple flowers commenced to open, v.-as not conducive to a heavy set. During 

 the bulk of the blooming period, cool, rainy -.veather Ij.mited the extent of polli- 

 nation. Under these conditions the set was not nec-rly at! g^roat as the bloom 

 indicated it mi^ht be, Elgetol applied to Red Astrachan^ Baldv.-in and Duchess 

 resulted in much more thinning and foliage injury thr.n similar single or double 

 applications of DN #1, Vifhere the set vjas heavy onoui^h to v/arrent thinning on 

 Yellavi Transparent, V/ealthy, Duchess, and Early Mcintosh, DW -jfl gave satisfactory 

 results. It no longer seems desirable to consider the liquid dinitro materials 

 for blossom thinning of apples. In the peach test, DN -^^289 reduced the set more 

 than equivalent concentrations of either DN #1 or El^jetol, 



j^plications of 8 oz, of App-L-Set per 100 gallons of spray at calyx time 

 eliminated the crop on Duchoss applo trees and r';sulted in severe leaf dwarfing 

 and distortion. Calyx applications of this material to Vfealthy, Mcintosh, and in 

 some instances Early Llcliitosh, thinned satisfactorily at calyx time with much less 

 foliage injury, App-L-Set appoo-rs to be more injurious to apple foliage v/hen 

 applied shortly after bloom than it does v/hon used at the same or higher concen- 

 trations two and four weeks after calyx. 



Tests at Amherst and in one graver's orchard, using up to 12 and 20 ounces 

 of App-L-Set per 100 gallons of spray two and four vciks,, respectively, after 

 calyx on Mcintosh, Golden Delicious, and Early Kcr'ntoi-h, show that chemical thin- 

 ning can be accompli. shed c.b this late date, A. trcotiuen'^ that oaii be made as late 

 as four weeks afi-'i.T cal'/>" h-.'.s 'he distinct advxi^o.FC f^ver ::■''!: ''^-cza or calyx applica- 

 tions since i.ha cictenb of fruit setting and the ne-; ?.:rsity ■f'or thniming can be 

 rather accurats'.y petnrm:-ri'-«i by that timeo Cf ocv-.-. s;.:. the oarlior thinning can be 

 done, the g-;eutoi are the ohai'jces of obtaining di^oj ru'^ lu ooiimeroial size with the 

 least reductioxa in yield vxid of mailing alternate bearing varieties bear more uni- 

 form, annual crops, 



— F, "vT, Southwick and VJ", D, Weeks 



LATE -SEASON C0NTR0_L OF APPLE SCAB 



The surect m v.y to prjvc'nt iate season infection of apple Scab is to have no 

 leaf or fruit inf ectM:!;. 7.']ivr. tha first of Au.;u'^t c\.-:rives.. Very few Llclntosh 

 growers in ,ivaf-".-:,'^hu^.c-;-:t£i ere jn that position ';his .y-'^r •— cr in aruy year for that 

 matter« A- lo";: £■'■ ,?•- -ivi Scab apjts aro pi'e'Sint in \he br^-es, :'i ths top 

 brai^chot' in par ■:le' .i.ar.^ there Is danger of i'vulv -'j;.fo'-.-':i.v,i, parti^ul•.^rly (1) after 

 the spray dop^'f.-;-.: f'-i-r^ -:.v:i h-.z-^ cOTor spray b.:.?omij'J '^utgr-OkVi o-' is leathered away, 

 and (2) if conrinuouf or f.nte mil- tent wet periods of sufficient duration occur 

 during August or Ssp-uenboru 



This year when many orchards sho^.T dangerous amounts of active Scab on the 

 foliage, even though very light infections may exist on tho fruits, grov^ors need 

 to know certain facts about requirements for fruit infection during the period 



