FINAL REPORT WTFRC Project # AH-1-5 WSU Project # 13C-355-3 Project title: PI: Orgniztion: Coopertors: of Sunburn in Apples with RAYNOX Lrry Schrder, Horticulturist WSU Tree Fruit Reserch nd Extension Center, Wentchee (59) 3-11 ext. 5; schrder@wsu.edu Jim McFerson, Tom Auvil, nd Tory Schmidt, WTFRC, Wentchee Leo Jedlow nd Jinshe Sun, WSU TFREC, Wentchee Objectives: 1. Estlish the optiml timing, rtes nd ppliction frequency of RAYNOX to pples for protection from sunburn.. Study efficcy of RAYNOX s stilizer or crrier for nutrients, growth regultors nd other compounds spryed on trees or fruit. Significnt findings: 1. RAYNOX effectively protects pples from sunburn dmge. In four yers of field testing in severl growers orchrds, RAYNOX nd Surround were similr in efficcy for sunburn protection. Both protectnts reduced sunburn out 5% on verge.. RAYNOX is liquid concentrte nd is esily diluted with wter in the spryer tnk. 3. RAYNOX does not interfere with color development. Fruit previously sunburned recovers better (i.e., color over) when treted with RAYNOX.. RAYNOX leves no unttrctive residue on fruit, in the clyx or in the stem bowl. 5. RAYNOX blocks substntil UV-B rdition, cuse of sunburn browning in pples.. RAYNOX lso reflects ultrviolet nd infrred rdition tht is normlly converted to het when sorbed by pples. Methods: Sunburn trils were conducted in growers orchrds during, 1 nd. Tretments were pplied with the Proptec low volume spryer. In, RAYNOX ws diluted 1:1 nd pplied t 5 gl/cre (gp). In 1, RAYNOX ws diluted so tht ppliction rtes were 1 or gp of RAYNOX concentrte. No significnt differences were observed between the two rtes during 1. Thus, only 1 gllons of RAYNOX concentrte were diluted nd pplied during. The incidence of sunburn ws evluted t different stges of mturity. At hrvest, fruit qulity nd size were ssessed to see if RAYNOX or Surround ffected these trits. In new experiment this yer, vrious formultions (i.e., Surround, RAYNOX, Vpor Grd, nd with wter s control) were pplied to Fuji pples strting in erly July to protect pples from sunburn. The incidence of sunburn ws very high in these plots. We devised new system for clssifying the extent of sunburn dmge. This more extensive evlution system llowed us to determine whether sunburned fruit recovered, becme more sunburned, or remined the sme fter September 9. Six evlution clsses were estlished s follows: Clss : no sunburn; Clss I: light yellow spot on the sun-exposed side; Clss II: more intense yellow spot; Clss III: yellow spot with pprent lenticel brekdown; Clss IV: drk tn spot; nd Clss V: necrotic spot. Ten pples in ech of five clsses (Clss through Clss IV) were tgged on September 9 in ech of the four tretments. With four replictions, pples of ech clss nd vriety were tgged. These fruits
were hrvested (October ) nd evluted gin to determine whether sunburn dmge incresed (i.e., sunburn dmge moved the fruit into higher clss), whether sunburn dmge ws less pprent due to coloring over, or whether fruits remined in the sme clss. Then ll fruits were plced in cold storge t Stemilt. The fruits will be evluted periodiclly to see if pigment chnges during storge cuse sunburn to become more visible in fruit of ech clss nd whether development of stin differs in the vrious clsses. Results nd discussion: Sunburn tril with Gl in : RAYNOX ws diluted 1:1 nd pplied t 5 gl/a (gp) on June 7, July 1, July nd August 7 (X) or on June 7 nd July (X) with Proptec tower spryer. On August 9, McFerson s tem found no significnt differences in sunburn between RAYNOX X (5.% sunburn) or RAYNOX X (.% sunburn) nd the control (5.% sunburn). Percent sunburn 1 1 1 Sunburn-Gl-.1. Surround X Surround X RAYNOX X RAYNOX X Fig. 1. Evlution of sunburn for Gl pples treted with vrious formultions On August 1, Schrder s tem found tht RAYNOX X (.% sunburn) nd RAYNOX X (.% sunburn) were significntly lower thn the control (1.% sunburn) (Fig.1). The higher incidence of sunburn observed on August 1 ws expected, s some of the highest fruit tempertures for the summer were recorded during the first hlf of August in Wentchee. In Wentchee, fruit skin temperture exceeded 113 F on 9 dys in erly August. It seems likely tht fruit temperture t this orchrd lso exceeded 113 F t lest once during tht intervl nd cused sunburn on fully exposed fruit. Sunburn tril with Fuji in : RAYNOX ws diluted l:1 nd pplied t 5 gp on June 7, July 1, July nd August 7 (X) or on June 7 nd July (X) with Proptec spryer. On August 9, McFerson s tem reported no significnt differences between RAYNOX X (.7% sunburn) or RAYNOX X (3.15% sunburn) nd the control (5.7% sunburn). On September, McFerson s tem found RAYNOX X (3.5% sunburn) to be better thn the control (.5% sunburn) but not different from RAYNOX X (.17% sunburn). On August, Schrder s tem found RAYNOX X (.9% sunburn) nd RAYNOX X (5.% sunburn) to be significntly better thn the control (1.59% sunburn) (Fig. ). On September, RAYNOX X (.53% sunburn) nd RAYNOX X (3.7% sunburn) were not significntly different thn the control (.7% sunburn).
In n experiment in Wentchee, we found tht sunburn event occurred on August. Fruit skin temperture (11 F) ws the highest for the seson tht dy in Wentchee. This my explin the lrge sunburn-fuji-.. Percent 1 1 RAYNOX X RAYNOX X Surround X Surround X Fig.. Evlution of sunburn for Fuji pples treted with vrious formultions. increse in sunburn observed t this site on August s compred to the August 9 evlutions. There ws only one time lter in the seson (i.e., September 1) when the fruit skin temperture reched 113 F t the Wentchee site, nd it is unlikely tht this cused sunburn in these Fuji. The observtion tht sunburn incidence ws lower on September thn on August is probly due to red pigment synthesis in September tht msked some of the sunburn browning. Sunburn tril with Cmeo in 1: In long-row tril conducted with Cmeo, sunburn ws reduced ~5% by RAYNOX t 1 gp nd by RAYNOX t gp (three pplictions mde with Proptec spryer) (Fig. 3). The incidence of sunburn ws firly high on pples in the upper prt of the cnopy. The evlutor stood on ldder nd evluted 1 pples ove the fourth wire of the trellis support system. There ws little sunburn in the lower prt of the cnopy, s pples were less exposed to the sun nd trees in n djcent row shded mny fruits. Sunburn in pples treted with RAYNOX t 1 nd gp ws significntly lower thn in the controls or Surround-treted fruit. Apples spryed with Micron Shde suspended in wxy mtrix or spryed with the mtrix lone were intermedite nd not significntly different thn either other group (Fig. 3). Sunburn recorded by McFerson s tem ws lower becuse the evlutor stood on the ground nd could not see the higher incidence of sunburn on fruit ner the top of the cnopy.
Percent Sunburn 1 1 1 1 1 b Sunburn in Cmeo, 1 b RAYNOX 1 gl/a RAYNOX gl/a Surround Mtrix Mtrix + Micron Tretment Fig. 3. Evlution of sunburn on Cmeo pples treted with vrious formultions. Tretments were pplied with the Proptec low volume spryer t 5 gp. Brs with the sme letter re not significntly different (P<.5) from ech other, ccording to the Duncn s Multiple Rnge Test. Sunburn tril with Gl nd Fuji in : During, experiments were conducted on Gl, Fuji, nd Grnny Smith. All tretments were pplied on four dtes: July 5, July, July, nd August 7. RAYNOX (1 gp) ws diluted nd pplied with the Proptec tower spryer t rte of 5 gp. Surround ws pplied t rte of 5 lb./cre on July 5 nd t rte of 5 lb./cre t lter pplictions. Vpor Grd ws pplied t rte of 1 gl/cre ech time. Sunburn ws evluted periodiclly, nd representtive dt re shown for Gl nd Fuji. With Gl evluted for sunburn on September, Surround suppressed sunburn more thn other tretments but ws not significntly different sttisticlly from RAYNOX (Fig. ). With Fuji evluted for sunburn on August 1, incidence of sunburn ws lowest in the RAYNOX-treted fruit, but RAYNOX nd Surround suppressed sunburn to nerly the sme extent (Fig. 5). By September 19, sunburn in Fuji ws substntilly higher for ll tretments due to sunburn events on September 11, 1, nd 13. Surround-treted pples hd the lowest incidence of sunburn, but were not different sttisticlly from pples treted with RAYNOX. Fruit treted with Vpor Grd showed the highest incidence of sunburn (Fig. ).
Sunburn-Gl-9// b b Percent Sunburn 1 9 7 5 3 1 Surround RAYNOXfull Vpor Grd Tretment Fig.. Percent sunburn observed in Gl on September,, fter four pplictions of three sunburn protectnts or wter (control). Brs with the sme letter re not significntly different (P<.5) from ech other, ccording to the Duncn s Multiple Rnge Test. Sunburn-Fuji-/1/ Percent Sunburn 35 3 5 15 1 5 Surround RAYNOXfull Vpor Grd Tretment Fig. 5. Percent sunburn observed in Fuji on August 1,, fter four pplictions of three sunburn protectnts or wter (control). Brs with the sme letter re not significntly different (P<.5) from ech other, ccording to the Duncn s Multiple Rnge Test.
Percent Sunburn 5 3 1 Sunburn-Fuji-9/19/ c bc Surround RAYNOXfull cly Vpor Grd Tretment Fig.. Percent sunburn observed in Fuji on August 1,, fter four pplictions of three sunburn protectnts or wter (control). Brs with the sme letter re not significntly different (P<.5) from ech other, ccording to the Duncn s Multiple Rnge Test. Study on Lte-Seson Chnges in Sunburn Injury in Fuji, : Some controversy exists out the extent to which sunburn injury is msked by lte-seson pigment chnges. Tht is, cn fruit tht hs mild sunburn injury ccumulte nthocynins or other pigments nd msk tht sunburn injury by hrvest time? We designed n experiment to trck the chnges tht occurred in Fuji fruit beginning September 9,, nd ending t hrvest on October. All fruits were re-evluted for sunburn on October, nd ny chnges from the previous evlution on September 9 were noted. Some fruit showed some recovery from the erlier sunburn dmge (Fig. 7). This ws especilly true for fruit treted with RAYNOX. About 1% of the fruit showed less sunburn injury thn on September 9. Some fruits were sunburned gin during the period between September 11 to 13 nd moved to clss with higher number indicting more serious sunburn (Fig. ). This ws especilly true for control nd Vpor Grd-treted fruit. Some fruits were sunburned so bdly tht they dvnced to sunburn necrosis (Clss V) on October (Fig. 9). RAYNOX-treted pples showed the lest necrosis on October.
Percentge of 'Fuji' Apples tht Recovered from Sunburn Browning between Sept. 9 nd Oct., Percent Recovered 1 1 1 1 RAYNOX Surround Vpor Grd Fig. 7. Percentge of Fuji pples on which some recovery from sunburn browning ws observed between September 9 nd October,. Percentge of 'Fuji' Apples tht Developed More Severe Sunburn Browning between Sept. 9 nd Oct., Percent of Fruit Developing More Severe Sunburn 35 3 5 15 1 5 RAYNOX Surround Vpor Grd Fig.. Percentge of Fuji pples tht developed more severe sunburn between September 9 nd October,. Conditions were fvorle for sunburn event on September 11 to September 13.
Percentge of 'Fuji' Apples tht Advnced from Sunburn Browning to Necrosis between Sept. 9 nd Oct., Percent Developing Necrosis 1 1 1 1 1 RAYNOX Surround Vpor Grd Fig. 9. Percentge of Fuji pples tht dvnced from sunburn browning to sunburn necrosis between September 9 nd October,. Modes-of-ction of RAYNOX: Qurtz crucibles (1 ml size) were coted with RAYNOX. After drying, the mount of light of vrious wvelengths tht pssed through (i.e., trnsmission) the RAYNOX nd crucible were mesured ner high noon on cler dy. Five sensors clibrted to detect different prts of the solr spectrum were used. UV-B trnsmission ws decresed more thn other types of light. For exmples, UV-B trnsmission through the crucible ws inhibited nerly % by 5% RAYNOX. We suggest tht RAYNOX protects fruit from sunburn by blocking trnsmission of substntil mount of the dmging UV-B to the fruit s surfce. Other studies with reflectometer hve shown tht RAYNOX reflects some of the UV-B. RAYNOX lso reflects some of the infrred rdition.
Budget: Project title: of Sunburn in Apples with RAYNOX PI: Lrry Schrder, Horticulturist Project durtion: 1- Project totl ( yers): $11, Yer Yer 1 (1) Yer () Totl 5,9 5,9 Current yer brekdown Item Yer 1 (1) Yer () Slries Benefits (%) Wges 1,, Benefits (1%) Equipment Supplies 7 7 Trvel Miscellneous Totl 5,9 5,9 1 Time-slip will help pply tretments, evlute trils, hrvest nd nlyze dt. Employee benefits re 1% of slries for time-slip wges. Summry of totl cost of project: $11,