Grant, Joseph A

Glozer Dr, Kitren

Monson, Maria :

Mitcham Dr, Elizabeth J

Evaluation of pre - harvest spray treatments on rain - induced cracking of Bing sweet cherry Principal Investigators : Joe Grant , Kitren Glozer , Maria Monzon and Elizabeth Mitcham Grower Cooperator : Pat Hale : 2005 Year Test Location : Wells Lane , ¼ mile north of Harney Lane , Lodi , California , USA , T3NR7E : â?? Bing â?? sweet cherry on Mahaleb rootstock , planted 1992 ; 6 % Lapins , Ranier and Black Test Crop Tartarian pollenizers : Randomized complete block design , ten replications , single - tree plots Plot design Treatments : Formulated product per acre Treatment Timing Date Product Bluestim 4.5 lb Early straw color development 29 April Bluestim 4.5 lb . 50 % pink fruit 13 May Bluestim 4.5 lb . Early straw and 50 % pink fruit 29 April and 13 May Rainguard 2.28 gal ( 10 % ) v / v Early straw and 50 % pink fruit 29 April and 13 May Untreated : No - Foam A ( 3 ounces / acre ) added to Bluestim treatments only Additives Application equipment : Backpack air - assisted mist blower sprayer Spray volume : 228 gallons per acre ( 2 gallons per tree ) . Methods : Rain - induced cracking : First harvest ( 17 May ) , approximately 100 fruit collected at random from north ( 50 fruit ) and Each fruit south ( 50 fruit ) sides of each replicate tree , representing all salable maturities ( colors ) . evaluated for fruit color ( 1 - 4 ; 1 = light red , 2 = red , 3 = dark red , 4 = mahogany ) , presence or absence ( 1 - 4 ; 1 = no crack , 2 < 0.25 â?쳌 crack , 3 = 0.25 - of cracking within color class , and severity of cracking 0.5 â?쳌 crack , 4 = > 0.5 â?쳌 crack ) . At second harvest ( 23 May ) , 100 fruit randomly harvested as above from Treatments 1 , 4 and 5 only . Fruit were evaluated for incidence and severity of cracking , as previously , without categorizing by color . Postharvest and post - storage fruit quality On May 17 , 150 fruit having no cracks or other defects were collected at random from each replicate tree and transported day to the Pomology Postharvest Laboratory , UC Davis . A total of 90 fruit for each treatment and replication were separated into three subsamples of 30 fruit each : 30 fruit to be used for initial quality evaluations and two 30 - fruit subsamples to be used for post - storage evaluations after simulated air and sea shipment storage . Initial quality was evaluated 24 h after harvest , following cold storage at 0 ° C overnight and warmed to 20 ° C before evaluation . Air shipment was simulated by storing subsamples in small vented polyethylene bags for 2 days at 5 ° C . Sea shipment samples were stored for 14 days at 0 ° C . Fruit from both storage treatments were subsequently held for 15 hours at 20 ° C and 90 - 95 % relative humidity to simulate market handling conditions . For initial and post - storage evaluations , firmness of individual fruit in each 30 - fruit subsample was measured using a FirmTech 2 Firmness Tester ( Bioworks , Inc . , Wamego , KS ) . A single sample of juice expressed from all 30 fruit in each subsample was used to measure fruit soluble solids and titratable acidity . Visual evaluations of stem browning , berry browning , pitting , cracking of the skin , decay , and overall â?? marketability â?쳌 were also conducted on each subsample using subjective ratings as follows : Statistical analyses : Rain - induced cracking : First harvest : Cracking incidence and severity were statistically analyzed for treatment effects alone and as an interaction with fruit maturity . Maturity was described as proportion of fruit sampled from each replicate tree in a given color class ( light red , red , dark red and mahogany ) . Severity of cracking was described on a 1 to 4 scale , with 1 = no crack , 2 < 0.25 " crack , 3 0.25 - 0.5 " crack , 4 = 0.5 " or bigger . Incidence of cracking was measured as the proportion of fruit in a given sample that were cracked . Logistics regression and contrasts ( SAS version 9.1 ; SAS Institute Inc . , Cary , NC ) were used to evaluate the incidence of cracking within each maturity class ( color ) , and then for mahogany fruit alone and dark red + mahogany fruit combined , versus light red + red fruit combined , to see if maturity as a function of treatment affected the incidence of cracking . The logistics model was used to normalize the data as a log of the odds ( y = logit ( p ) = ln ( p / 1 - p ) . The logistics regression model took the form of : cracked / total = treat | color rep ( treat ) . Total cracking was determined by this model and treatment effects were compared by contrasts and chi - square ( SAS ) . Cracking severity as a function of treatment and maturity We then class ( color ) was analyzed by contrasts . We first compared crack type 1 to crack types 2 , 3 , 4 . compared each type of crack ( 2 , 3 , 4 ) to all other combinations ( 2 vs 3 , 2 vs 4 , 3 vs 4 ) . We also analyzed this data by combining crack types crack types 3 + 4 together ( which , by default , combined crack types 1 + 2 together ) . The premise is that type 1 crack is no crack - to negligible size of crack and crack types 3 and 4 would be always culled . In a very bad rain - cracking year , some crack types 2 might get packed . Mean separation was by least means squares . : Fruit data was statistically analyzed as before , without reference to maturity of the fruit . Second harvest Harvest and post - storage fruit quality A 2 - way factorial design was employed for each shipment / treatment combination with ten 30 - fruit subsamples from each of 10 replications with 30 subsamples . Fruit quality characteristics were measured for each subsample and values were averaged to have a total of 10 replicates for each shipment / treatment combination . Analysis of variance was computed by SAS Version 8.0 ( SAS Institute Inc . , Cary , NC ) . Multiple mean comparisons were performed using Tukey - Kramer adjustment . Results and Conclusions : Rain - induced cracking Measurable rainfall was recorded 27 - 28 April , 4 - 5 May , 8 - 9 May and 15 - 16 May ( Figure 1 ) . All but the last of these rainfall events were of a magnitude and timing ( with respect to development of fruit ) to cause fruit cracking . The relative contributions of each April and early May event to cracking observed at harvest are unknown , though we observed little fruit cracking in the orchard while applying the first treatments on 29 April . Thus we tentatively attribute most of the cracking recorded at harvest to the May rain events , which occurred after the first spray treatments , but before the second . First harvest : There were no differences among treatments in fruit maturity , as measured by the percentage of fruit in each color class at harvest . , the color with the highest incidence When cracking incidence was measured by color across treatments of cracking was mahogany and that with the least was light red ; differences among color classes were highly significant ( data not shown ) . This is not surprising , as the common observation among growers and researchers alike , has been that rain - cracking incidence increases with maturity of the fruit . In comparing treatment and maturity effects on rain cracking , we found that the total percentage of was increased by Rainguard ( Table 1 ) . The single Bluestim application cracking across all colors treatments were not different from the untreated control . The double application of Bluestim , however , reduced total cracking significantly compared to all other treatments . When cracking was evaluated within color classes , we found that cracking was significantly different among treatments in all colors but mahogany . Rainguard significantly increased the percentage of fruit with cracks 0.25 â?쳌 and larger compared to untreated and late and double Bluestim - treated fruit , but not compared to early Bluestim - treated fruit ( Table 2 ) . : Cracking increased slightly between the first and second harvest . Cracking of double Second harvest Bluestim treated fruit was not significantly different from untreated fruit ( Table 3 ) . Rainguard treated fruit had more fruit with 0.25 â?쳌 and larger cracks than untreated fruit , as in the first harvest . Harvest and post - storage fruit quality Cherry firmness was affected by spray treatment and postharvest storage regime . ( Table 2 ) . Raingard treated fruit were significantly more firm in the initial evaluation and after simulated sea shipment compared to fruit from other treatments . Simulated air shipment reduced fruit firmness compared to the initial and sea shipment storage ( Fig . 1 ) . The soluble solids content showed minor differences among each shipment / treatment combination ( Table 3 ) . Fruit from the red treatment had more soluble solids within each shipment compared to the rest of the treatments . The titratable acidity was affected by shipment and treatment ( Table 2 and 4 ) . Fruit that had been stored for simulated sea shipment were significantly less acid compared to the initial and simulated air shipment fruit , perhaps the solubles in the fruit stabilize after a longer storage period . Regardless of the shipment , fruit from the red treatment had higher acid levels compared to the other treatments . Berry pitting , skin cracking and decay were only affected by the shipment storage type ( Table 2 and 5 ) . While there was no stem browning or berry browning following air shipment and results show that there was some stem and berry browning following sea shipment ( Fig . 2 and 3 , respectively ) . However these values were very low and did not affect fruit marketability ( Fig . 4 ) . Interesting that double Bluestim reduced cracking even though second app was after rain events . The quality of â?? Bing â?? sweet cherries was affected more by the shipment type than the treatment ( Table 2 ) . There were minor differences between treatments in firmness , Although fruit that had been stored for simulated sea shipment had a lower quality compared to the quality of the initial and simulated air shipment , the fruit quality was well within marketability limits . Figure 1 . Daily rainfall recorded at Live Oak Station ( San Joaquin WEATHERNET ) , 1 mile from test orchard , = Spray treatments applied . 0.5 0.4 inches 0.3 Dailyrainfall , 0.2 0.1 0 10 - Apr 13 - Apr 16 - Apr 19 - Apr 22 - Apr 25 - Apr 28 - Apr 1 - Apr 4 - Apr 7 - Apr 22 - May 10 - May 13 - May 16 - May 19 - May 4 - May 7 - May 1 - May Mahogany ns 61.8 58.5 71.9 65.8 65.8 fruit cracked red bc bc ab a c 70.1 52.7 58.7 58.3 63.3 2005 . Dark of 2005 . fruit 0.5 â?쳌 percentage of May > ab ab a b b May cracks Percentage 30.1 22.6 21.2 27.1 24.7 17 bc cd a d b 17 Red Within - color 58.1 harvest 27.1 40.1 30.6 35.1 with harvest respectively . respectively . first first fruit Percentag 0.25 - 0.5 â?쳌 0.5 â?쳌 x bc bc ab cracks red a abc rain - cracking , c bc with 32.7ab c a 44.2 rain - cracking , 28.8 33.9 37.5 33.1 Light 18.4 31.2 of 23.1 > 25.3 + e significant , significant , pink pink % cracked colors 50 % of 50 % x crack . a b b b of c non incidence and non 57.9 47.2 47.8 41.9 36.2 and all severity Treatment 0.001 , Total 0.001 , straw for 0.5 â?쳌 straw straw pink early > = on on crack , early early = ns 50 % ns pink cherries cherries * * * , pink Rainguard , * * * , Bluestim , Bluestim , Bluestim , Untreated 0.25 - 0.5 â?쳌 50 % 0.05 % ) : 50 % 0.05 % ) : sweet sweet and Treatment and crack , straw = straw straw = â?? Bing â?? â?? Bing â?? pink cracking ( P 236.2 * * * 547.7 * * * 62.0 * * * 41.1 * * * ( P 0.5 â?쳌 squares early squares 0.25 â?쳌 early early 50 % > of of Rainguard , of Bluestim , Bluestim , Bluestim , Untreated severity < means maturity maturity Chi - Square means crack , 0.5 â?쳌 least least 187.4 * * * 666.2 * * * no > 44.8 * * * 25.3 * * and and Chi - + crack : 547.7 * * * 236.2 * * * 61.9 * * * 41.1 * * * 0.25 - 0.5 â?쳌 and Square Wald and treatment treatment Wald contrasts contrasts of size df 12 45 df 12 45 4 3 of of by 4 3 by by Effects Effects measured separation ( maturity ) ( maturity ) separation Treat * color Treat * color Treatment Treatment Rep ( treat ) Rep ( treat ) 1 . 2 . Severity Means Effect Effect Table Table Color Color Mean 0.25 - 0.5 " > 0.5 " a a a a a a b b Sea 0.98 1.02 0.97 0.97 0.98 36.9 22.4 20.1 category + shipment . cracking abc bc > 0.5 " ab b b a c a Air 6.4 5.6 17.4 1.04 1.12 TA 1.05 1.09 1.07 % each sea 0.25 - ab 0.5 " a b or in 16.0 19.4 14.5 Initial ab a a b b fruit air 1.12 1.13 1.05 1.05 1.08 2005 . simulated of < 0.25 " ns Percentage 11.2 May , 12.6 10.9 respectively . and a a a a a 23 cracked b a Total b Sea 19.1 18.7 18.5 19.0 18.8 33.6 49.5 31.0 harvest treatment significant , ab a a a b straw Air second 19.1 19.0 19.4 SS 17.8 pink 18.7 control following Treatment early % early 50 % pink crack cherry , 0.05 ) non Rainguard , Initial ab ab a a b Bluestim , Untreated and 0.001 , 19.3 19.3 18.4 19.1 18.8 50 % 0.5 â?쳌 fruit = straw sweet ( P and adjustment > = crack , cherry ns 0.25 - 0.5 " â?? Bing â?? * * * , > 0.5 " 16.2 * * * ab a b b b Sea 0.25 - 0.5 â?쳌 sweet 364 329 324 329 343 7.9 0.05 % ) : Tukey - Kramer + in severity â?? Bing â?? rain - cracking Firmness 19.0 * * * > 0.5 " crack , a a a a a = Air 11.9 306 297 293 300 297 ( P cracking of squares 0.25 â?쳌 content using 0.25 - 0.5 " of 7.1 * Initial of ab ab ab a < b 12.2 means crack , performed Chi - Square 342 312 severity 314 321 317 solids least < 0.25 " no 2.7 15.9 soluble crack : pink on evaluation and pink Wald treatment contrasts 50 % of 50 % cracked for 15.3 * * * Total size and values 9.8 within & by of straw by straw straw pink measured Effects separation df separation 2 9 Mean early early early 50 % Treatment Treatment Raingard , Bluestim , Bluestim , Bluestim , Untreated 4 . 3 . Severity Means Effect Table Table Mean Rep poor transport very unsalable , condition sea Overall a a a a a a a a a a a a a a a 00.0 0.00 00.0 00.0 00.0 0.0 0.0 0.0 0.0 0.0 0.4 0.7 0.7 0.6 0.5 and air = 3 simulated salable ; browning Fruit a a a a a a a a a a a b b b b 0.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.0 0.0 0.1 still following but damage browning ab ab ab a a a a a a a a a a a b Stem 0.5 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.3 and 0.3 0.4 0.4 obvious severe harvest = z = commercial 3 Decay a a a a a a a a a a a a a a a 2 moderate , salable ; 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.1 0.1 0.1 0.1 0.05 ) and = z at Cracking 2 good slight , a a a a a a a a a a a a a a a = cherries 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.6 0.6 0.4 0.6 0.5 ( P 70 - 100 % adjustment still = but 1 â?? Bing â?? none , = damage 4 z Pitting and a a a a a a a a a a a a a a a Tukey - Kramer = of 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.1 0.1 0.0 0.1 0.1 51 - 75 % , 0 attributes visually : some = = 1 pink pink pink pink pink pink evaluated good ; 3 quality using 26 - 50 % , 50 % 50 % 50 % 50 % 50 % 50 % very performed Treatment on browning & & & & & & = = straw straw straw treatments straw straw straw straw straw straw 2 pink pink pink 0 1 - 25 % , visually : early early early early early early evaluation early early early 50 % 50 % 50 % fruit = Raingard , Raingard , Raingard , Bluestim , Bluestim , Bluestim , Bluestim , Bluestim , Bluestim , Bluestim , Bluestim , Bluestim , Untreated Untreated Untreated 1 and evaluated spray none , decay within of = Effects 0 cracking , condition separation browning : transport transport Evaluation 5 . storage . Harvest Overall Pitting , Table Mean Stem Air Sea