Southwick, Stephen :

Grant, Joseph A

Glozer Dr, Kitren

â?¢ â?¢ â?¢ â?¢ â?¢ â?¢ â?¢ â?¢ Project Title : Evaluation of Mahaleb rootstock selections 2004 Project Leader : Steve Southwick , Pomologist , Pomology Department , U . C . Davis Cooperators : Joe Grant , Farm Advisor , San Joaquin County Kitren Glozer , Staff Research Associate , Pomology Dept . , U . C . Davis 4 : Summary 200 In March 1995 , we planted the first of five rootstock trials to evaluate new mahaleb rootstocks that are thought to be resistant to Phytophthora spp . Site 2 in Stockton ( planted 1996 ) and Site 3 ( University of California , Davis ) planted in 1998 , were budded with â?? Bing â?? clone IR 83 - 2 - 5 . Site 2 was a large replicated trial and provided critical data through the years . Trial sites were compared until 2003 and mahaleb selections 155 - 1 , 156 - 5 , and 159 - 5 identified for release . In 2004 , we evaluated tree survival ( % ) , fruit maturity , cropping ( by rating and yield ) of â?? Bing â?? cherry as influenced by rootstock at site 2 . Year - to - year variation exists in horticultural performance indices , as is expected due to factors such as annual weather conditions , pruning , limb loss and tree - to - tree variability . Performance for most clones in 2004 was consistent with that seen in previous years . The previously selected rootstocks continue to be among those showing superior characteristics . Problem and its significance : Prunus mahaleb is one of the leading rootstocks for sweet cherry growers in California , but is susceptible to root and crown rot fungal diseases generally known as Phytophthora spp . Growers have experience with mahaleb and , other than being susceptible to Phytophthora disease , it is suitable for California growing conditions . Mahaleb trees from seed are drought tolerant , moderately resistant to bacterial canker and hypersensitive to Western - X . Mahaleb produces few root suckers , but gophers damage trees on mahaleb . Within the population of mahaleb clones that have been tested in the field are those that reduce tree size , have degrees of resistance to Phytophthora spp . , and alter the branching and bearing habit of â?? Bing â?? . It is well known that there are many mahaleb clones , but they have not been critically examined in the field under California conditions . From 48 mahaleb clones screened for Phytophthora susceptibility and vegetative rooting ability , approximately 20 were selected for their effect on horticultural characteristics . The field evaluation of these mahaleb clones is a natural evolution in the development of improved cherry rootstocks . By evaluating these Phytophthora resistant mahaleb clones for their horticultural ( tree size , suckering , fruit size , yield ) effects , clear separation of mahaleb clones can be made based upon performance in the field and growers can make more informed decisions about which â?? mahaleb â?쳌 is best for them . Development of these superior mahaleb clones is also compatible with current and future trends in tree training and pruning of sweet cherries in California . : Field evaluation of vegetatively propagated mahaleb selections for various Objectives horticultural characteristics and survival under field growing conditions with disease ( i.e . Phytophthora ) pressure . s : Plans and Procedure Locations and plant materials : On 15 February , 1996 a mahaleb rootstock trial was planted in the Lodi / Stockton area ( Site 2 ; cooperator Lodi Farming ) . Trees were planted at a spacing of 18 feet between rows and 13 feet between trees . The cultivar was â?? Bing â?? and the pollenizers were â?? Rainier â?? / mahaleb ( 8.3 % ) and â?? Black Tartarian â?? / Colt / Mazzard ( 8.3 % ) . Pollenizers were planted as every fourth tree in alternate rows ; replicates were planted as a randomized block design . The soil was a Wyman clay loam and the trees were irrigated by impact sprinklers . Trees were headed at planting to a height of 20 inches and current seasonâ??s shoots were headed during the summer at 18 inches . The training system was open center . Standards of mahaleb , and Mazzard were planted for controls . Survival , fruit maturity and crop evaluation : Death from Phytophthora and non - specified reasons ( % survival ) has been evaluated and recorded annually in July to September and during the dormant season . Site 2 started cropping in 2000 and we rated fruit maturity and crop load in 2004 using a signified rating system ( Table 1 ) . Fruit maturity was evaluated on a scale of 1 to 9 , in which 1 fruit mostly at â?? color break â?? ( straw - colored with pink suture and / or pink speckled skin ) , 5 signified â?? light Crop red â?? ( minimum maturity red ) , and 9 signified â?? mahogany â?? , ( CTIFL chips 1 and 4 , respectively ) . load was also rated on a scale of 1 to 9 , with 1 signifying little or no crop , 5 , and average crop , and 9 , over - cropped . Yields were calculated from the weight of all fruit harvested . n : Results , Site 2 Stockto Tree survival : The clonal rootstocks were initially tested by stem inoculation and soil flooding tests against strains of Phytophthora and found to show some promise with regard to tolerance or resistance . Under field tests there is pressure from stem pitting and Phytophthora sp . , as well as unknown mortality . Survival in 2003 was highest ( 100 % ) with mahaleb clones 155 - 1 , Small Turkish , and P50 ( Table 1 ) . Survival rates were next highest in Standard Mazzard ( 93 % ) , 156 - 5 ( 92 % ) , 162 - 1 ( 87 % ) , NY 34 ( 85 % ) , and P1 Large Leaf ( 80 % ) . Other mahaleb selections under test ranged from 87 to 25 % survival and Standard mahaleb had 55 % survival . Survival was unchanged in 2004 . Fruit maturity : Fruit maturity was most advanced in selections 297 - 2 , 159 - 5 , 156 - 5 , P2 small , but were not statistically different from standard mahaleb and selection 155 - 1 ( Table 1 ) . Crop load rating and yield : Highest crop load rating per tree was noted in rootstock selection 294 - 3 , but other selections including 156 - 5 , 295 - 3 , 159 - 5 , P2 small , NY 34 , 155 - 1 and others had similar crop load ratings ( Table 1 ) . Mazzard was the rootstock among the lowest with regard to crop load rating . Yield in 2004 was highest for 294 - 3 , which had been among the consistently - highest yielding clones in previous years . Clones with yields statistically equivalent to that of 294 - 3 include : 295 - 3 , Standard mahaleb , 163 - 1 , 141 - 1 , NY 34 , 297 - 2 , 162 - 1 , Small Turkish , 299 - 3 and 156 - 5 . 155 - 1 yielded similarly to previous years â?? i.e . in the mid - range group . 159 - 5 is a smaller tree , with a dwarfing habit and thus , yields continue to be lower than most other clones . Deleted : Standard mahaleb , Cumulative yields were highest for 294 - 3 , followed by 156 - 5 , 162 - 1 , standard mahaleb , 299 - 3 , 163 - 1 , NY 34 , small Turkish , 295 - 3 , 141 - 1 , 10 - 4 , 297 - 2 , 155 - 1 , P2 small leaf , 136 - 2 , 759 - Deleted : 299 - 3 , 163 - 1 , 295 - 3 , 2 , dwarf mahaleb , P1 LL , 251617 , 159 - 5 , standard mazard , and P50 . The cumulative yields were Deleted : 141 - 1 , highly variable among rootstocks ( Table 2 ) Deleted : Small Turkish , Deleted : P2 Small leaf , Deleted : 155 - 1 Summary to Date : Deleted : . Site 2 , Stockton : â?¢ Survival highest in mahaleb 155 - 1 , P50 , Small Turkish and 156 - 5 ; other clones ranged from 25 - 87 % survival and Standard mahaleb had 55 % . â?¢ Most clonal rootstocks were equivalent in vigor , with 299 - 3 representative of the most vigorous . Among the least vigorous were 159 - 5 , 163 - 1 , 141 - 1 , and 136 - 2 . â?¢ Earliness of bloom : Most advanced = 297 - 2 and 294 - 3 ( 2002 and 2003 ) , 156 - 5 , P2 small leaf and Standard mahaleb . Most delayed = Standard Mazzard , Colt and P50 . â?¢ Fruit size was statistically and numerically similar among rootstocks , and could to be due more to crop load , assuming pruning to be similar â?¢ Highest 2003 yield per tree was found with selection 156 - 5 ; this yield was statistically higher than that of Standard mahaleb . Highest 2004 yield per tree was found with selection 294 - 3 , although this was statistically equivalent to Standard mahaleb and several other selections . Standard Mazzard continues to be among the lowest yielding . Many selections evaluated in 2003 and 2004 had statistically equivalent yields . Highest cumulative yield per tree over 4 seasons were noted with selections 294 - 3 and 156 - 5 . The lowest cumulative 4 year yields per tree were noted with P50 and Standard Mazzard , although a few other selections are as low , including 159 - 5 . Other rootstocks were intermediate with regard to the 4 year cumulative yield per tree . â?¢ Yield efficiency was similar among clonal selections in 2003 . â?¢ Fruit maturity was advanced for selection 297 - 2 , but mostly fruit maturity was similar among evaluated rootstocks . â?¢ Root and trunk suckers were found on all selections in 2002 , but prevalent on none ; 299 - 3 produced the greatest number of root suckers and 251617 the greatest number of trunk suckers Site 3 , UCDavis : â?¢ Colt , Standard mahaleb and Standard Mazzard had survival of 40 , 50 , and 20 % , respectively . 155 - 1 had 100 % survival . Several other mahaleb clones had higher survival rates than the standards â?¢ In the low chill year of 2002 , bloom abundance was statistically equal among clones , Standard mahaleb and mazzard ; Dwarf mahaleb was among the highest and Colt was one of the lowest . â?¢ There was a fair degree of variation in earliness of bloom in 2003 . 136 - 2 and 11 - 4 had early bloom in 2002 and 2003 . Medium Turkish was most early , but not statistically different compared with other selections . Colt and Standard Mazzard had most delay in bloom and Standard mahaleb was intermediate and statistically equivalent with many other selections . Site 5 , Stockton : â?¢ Survival was high for all trees ; single trees of P1 Large leaf and 163 - 1 died . â?¢ 156 - 5 was the least vigorous of all rootstocks tested in 2003 . NY 34 was the most vigorous of the rootstocks and Standard mahaleb was the next most vigorous . Colt was less vigorous than Standard mahaleb , but more vigorous than selection 156 - 5 . The other rootstocks had statistically similar tree growth among the intermediate group . Conclusions : e have selected three rootstocks for commercial release : MH 155 - 1 , MH 156 - 5 and MH 159 - 5 . Deleted : Tree evaluation may continue . W Currently w Each of the three provides uniformity compared with seed - propagated mahaleb rootstocks . MH 155 - 1 and Deleted : The 3 rootstocks are listed MH 156 - 5 have greater survival in our test sites compared to standard mahaleb ( Table 1 ) . Cumulative below with their most important features . crop yields for four years indicate no statistical differences among MH 155 - 1 , MH 156 - 5 and standard mahaleb . MH 159 - 9 has cumulative yields significantly below that of standard mahaleb . The yield data ( Table 2 ) are highly variable and may not be predictive of long - term yields . They should , therefore , be interpreted with caution . MH 156 - 5 and MH 159 - 5 show tree - size reduction compared to standard mahaleb . The 3 rootstocks are listed below with their most important features . Features of MH 155 - 1 : · Uniformity of plant material compared with seed - propagated mahaleb · 100 % survival at all test sites ( higher than Standard mahaleb ) that had histories of Phytophthora and stem pitting · Low root and trunk sucker production · Full size tree comparable to standard seed - produced mahaleb , vigorous · Fruit size , yield comparable or greater than standard in 2 years out of 4 Features of MH 156 - 5 : · Uniformity of plant material compared with seed - propagated mahaleb · Survival is high at all test sites to date ( higher than Standard mahaleb ) , slightly below MH 155 - 1 · Low root and trunk sucker production · Precocious , early high yields with â?? Bing â?? · Tree size reduction about 5 to 10 % compared with standards ( significantly less at one site after 3 years ) ; increased yield efficiency · Fruit size , yield comparable or greater than standard · Has advanced bloom in some seasons with â?? Bing â?? Features of MH 159 - 5 : · Uniformity of plant material compared with seed - propagated mahaleb · Survival comparable to Standard mahaleb · Tree size reduction by approximately 15 to 20 % compared with standards · Suitable for higher density planting , increased yield efficiency overall · Low root and trunk sucker production · Precocious fruit flowering and fruit production · Fruit size , yield comparable to or greater than standard in 3 years out of 4 · Low doubling , spurring and deep suture production even with smaller tree · Has advanced bloom in some seasons with â?? Bing â?? Table 1 . Survival , fruit maturity and crop load of â?? Bing â?? / mahaleb selections , Site 2 Stockton ( Lodi Farming ) on 14 May , 2004 . No change in survival was found after June , 2003 . z y Cropload rating Selection % Survival Maturity rating x 3.00 cdef 251617 33 3.00 f P1 LL 80 3.50 bcdef 3.08 cdef 295 - 3 25 4.17 abcd 4.67 ab 159 - 5 40 4.29 ab 4.43 abc Std mahaleb 55 4.20 abcd 4.80 ab Dwarf mahaleb 50 3.67 abcdef 2.67 ef 10 - 4 59 4.00 abcde 3.70 bcde 294 - 3 62 4.22 abc 5.22 a 155 - 1 100 3.60 abcdef 3.40 bcdef Std Mazzard 93 3.46 bcdef 2.92 def P2 Small 31 4.25 ab 4.25 abcd 759 - 2 60 3.11 ef 3.33 bcdef 163 - 1 64 4.11 abcd 3.89 abcde 141 - 1 44 3.30 def 3.90 abcde NY 34 85 4.09 abcd 4.00 abcde 297 - 2 33 4.43 a 4.29 abcd 162 - 1 87 4.00 abcde 3.85 abcde 136 - 2 56 3.67 abcdef 3.50 bcde Small Turkish 100 4.20 abcd 3.90 abcde 299 - 3 43 3.33 cdef 2.67 ef 156 - 5 92 4.33 ab 4.67 ab P50 100 2.94 f 2.06 f Statistical significance : Rootstock * * * * * * x Means separation within columns by Duncanâ??s Multiple Range test . * * * indicates significance at the 0.1 % level . y Crop load rating 1 - 9 , with 1 = little or no crop , 5 = average crop , 9 = over - cropped . z Maturity rating 1 - 9 , with 1 = fruit mostly â?? color break â?? ( straw - colored with pink suture and / or pink speckled skin ) , 5 = light red ( minimum maturity red ) , 9 = mahogany . Table 2 . â?? Bing â?? / mahaleb selections planted 15 Feb 1996 , Site 2 Stockton ( Lodi Farming ) ; yield and cumulative yield in 2001through 2004 . Yield ( kg ) Cumulative yield Selection 2001 2002 2003 2004 2001 - 2003 2001 - 2004 X 21.7 28.6 bcd 32.4 bcd 52.3 bcd 92.7 c - g 251617 2.0 e P1 LL 26.7 a - d 9.9 20.8 cd 27.0 b - e 57.4 bcd 99.6 b - f 295 - 3 31.8 a - d 26.4 41.4 ab 44.4 abc 99.6 ab 126.8 a - e 159 - 5 23.0 a - e 28.9 21.7 cd 19.0 de 73.6 bc 75.8 efg Standard mahaleb 27.5 a - d 26.8 25.6 bcd 45.4 ab 79.9 bc 143.3 abc Dwarf mahaleb 24.4 a - d 20.4 20.4 cd 25.0 cde 65.2 bcd 87.0 d - g 10 - 4 32.3 a - d 19.6 35.2 bc 35.1 bcd 87.1 abc 123.7 a - e 24.9 294 - 3 34.5 abc 45.2 ab 54.7 a 104.6 a 158.5 a 155 - 1 16.9 b - e 27.4 29.9 bcd 27.6 b - e 74.2 bc 114.4 a - f Standard Mazzard 11.6 cde 13.0 14.5 cd 18.7 de 39.1 d 63.1 fg P2 Small 23.5 a - e 13.4 28.7 bcd 33.5 bcd 65.6 bcd 112.5 a - f 759 - 2 28.4 a - d 17.1 25.9 bcd 32.7 bcd 71.4 bc 106.0 a - f 163 - 1 28.9 a - d 22.5 32.2 bcd 40.8 abc 83.6 bc 132.0 a - d 141 - 1 38.3 ab 18.3 30.6 bcd 42.5 abc 87.2 abc 125.8 a - e NY 34 36.6 ab 17.9 37.8 bc 39.7 abc 92.3 ab 130.0 a - d 297 - 2 29.6 a - d 22.5 39.4 bc 42.3 abc 83.0 bc 123.3 a - e 162 - 1 32.5 a - d 12.7 40.7 b 39.8 abc 85.9 bc 144.6 abc 136 - 2 25.9 a - d 24.5 22.7 cd 31.9 bcd 88.7 abc 108.2 a - f Small Turkish 29.3 a - d 23.7 39.1 bc 36.9 a - d 92.1 ab 127.7 a - e 299 - 3 22.4 a - e 13.3 17.2 cd 41.6 abc 59.2 bcd 135.7 a - d 156 - 5 44.8 a 16.6 49.3 a 35.7 a - d 110.7 a 152.8 ab P50 10.8 de 22.7ns 9.0 d 12.9 e 42.5 cd 44.3 g X Mean separation within columns by Duncanâ??s multiple range test , P = 0.05 ; ns = non significant .