Southwick, Stephen :

Glozer Dr, Kitren

CALIFORNIA RESULTS 2003 ANNUAL REPORT OF NC - 140 SWEET CHERRY ROOTSTOCK PROJECT : NC - 140 , California COOPERATING AGENCIES AND PRINCIPAL LEADERS : Stephen M . Southwick * , Extension Specialist Kitren Glozer , Staff Research Associate Pomology Department , UC Davis , CA 95616 Progress of Work and Principle Accomplishments : Our first NC - 140 sweet cherry rootstock trials initiated in 1987 and 1988 as part of the NC - 140 project were terminated in 1994 because of tree decline from stem pitting disease . A final report was submitted at that time . Since then , from the group of new rootstocks tested , growers in California have ordered primarily 148 / 1 and 148 / 2 Gisela rootstocks , although Prunus mahaleb seedling is the primary rootstock of choice . The sweet cherry industry is rapidly expanding . We have initiated new experiments with grower cooperators . Introduction : The major rootstocks used for sweet cherry in California include Prunus mahaleb L . ( mahaleb ) , P . avium L . ( Mazzard ) , and â?? Colt â?? ( P . avium x P . pseudocerasus ) . Mahaleb is easy to propagate from seed , but has the disadvantage of susceptibility to root and crown rot fungal diseases generally known as Phytophthora spp . Mahaleb is drought tolerant , moderately resistant to bacterial canker and hypersensitive to Western - X . Mahaleb produces few root suckers , but gophers damage trees on Mahaleb . Mazzard is graft compatible with sweet cherry cultivars , but is slow to fruit and imparts vigor to the scion . Cherry fruit size is good on fully mature trees with Mazzard rootstock . â?? Bing â?? cherries trees on â?? Colt â?? rootstock show field resistance to cherry stem pitting ( CSP ) disease , an apparently soil - borne pathogen suspected to be of viral origin . Use of â?? Colt â?? is presently the only available option for mitigating the risk of CSP . California growers report varied and often poor performance of â?? Bing â?? cherry nursery grafted to â?? Colt â?? rootstock . Tree vigor is variable and seems to be site - and management - dependent . Trees planted on fine - textured soils are generally vigorous , non - precocious , have poor fruit set , and small soft fruit . On coarse - textured soils , tree size and vigor are reduced , trees tend to be more precocious with acceptable fruit size and quality . â?? Colt â?? is sensitive to crown gall and apparently requires higher chilling than mahaleb . The standard rootstocks for California sweet cherry production listed above do not serve all locations , growing conditions or cultivars of scion . The current rootstocks are increasingly challenged to perform under diverse conditions , particularly as new cultivars are developed as a function of California cherry production expansion into lower chilling and higher heat areas . It is unlikely that a single rootstock will ever be suited to all the environmental conditions and clonal or varietal diversity in which sweet cherry is grown . Field - testing of rootstocks must be used to determine which rootstocks are most appropriate for local growing conditions and management practices . Trials must examine the effects of rootstock on growth habit of the scion , cropping , survival and tolerance for unfavorable climatic conditions , and susceptibility to disease . Characteristics such as vigor , precocity , and compatibility must be evaluated . To this end , relatively new clonal rootstocks resulting from interspecific hybrid crosses have been tested as part of the ongoing NC - 140 Regional Trials . These trials include rootstocks of the â?? GM series â?? ( from Belgium ) , the â?? GI series â?? ( Giessen , Germany ; â?? Gisela â?? ) , â?? MxM â?? series ( Mazzard x mahaleb from Oregon ) , and mahaleb clones ( originally selected in Bordeaux , France ) . Our first trial begun in 1987 - 8 and terminated in 1994 , resulted in the following observations : $ Gi rootstocks induce dwarfing of â?? Bing â?? compared to Colt , mahaleb , mazzard , Stockton morello or MM series . $ Many Gi rootstocks induce early or precocious bearing in â?? Bing â?? . This feature is impressive early in the life of the orchard , but as trees get older ( 5 years or more ) there appears to be a tendency for overcropping and reduced fruit size . $ At present , there is no reliable way to regulate cropping with these rootstocks . Pollination management , extensive renewal pruning , gibberellin use to reduce flowering or other bloom thinners are possible means by which to reduce crop potential , but at present these possibilities are under study . $ Until 1994 , some of the best Gi rootstocks overall ( low root suckering , few bacterial canker symptoms , high yielding with good fruit size , dwarfing / improved yield efficiency , and enough vigor ) included : Gi 195 - 2 , Gi 148 - 1 and , possibly , Gi 169 - 15 . $ Standard mahaleb continues to be a good rootstock . Phytophthora root and crown rots can be problematic and partially reduced by careful irrigation . $ Tree size with Std mahaleb might be controlled through regulated deficit irrigation , summer and selective pruning . â?? $ Precocity can be induced by tree training . $ By using mahaleb rootstocks the number of trees per acre will not be as high as with dwarfing rootstocks . More importantly , the level of cropping is easier to control and the level of experience in handling trees growing on mahaleb is greater than with the Gi series rootstocks . Materials and Methods â?? 1998 to 2003 Planting , Pruning and Training . Rootstocks were propagated by Meadow Lake Nursery in Oregon and were budded with â?? Bing â?? in 1997 . At least eight replicates of 16 rootstocks were planted on 27 April , 1998 at the University of California , Davis , Pomology Departmentâ??s Wolfskill Experimental Orchard in Winters , California . The soil was classified as a Yolo clay - loam . Tree spacing was 10 ' x 16 ' , planted on berms and irrigated with microsprinkers . Trees were headed at 24 " at planting . The experimental design was a randomized complete block with eight individual tree replicates . Rootstocks are listed in Table 1 . Pollenizers included â?? Chinook â?? / MH ( mahaleb ) , â?? Larian â?? / MH , â?? Black Tartarian â?? / MH , â?? Early Burlat â?? / MH , â?? Vista â?? / MH , and â?? Van â?? / Maz ( Mazzard ) . Single leader training has limited use and with the long growing season of California we elected to follow the scion growth habit ( upright vs spreading ) as a function of rootstock . Mahaleb and Mazzard rootstocks were used as controls ; â?? Colt â?? was added as an additional control in a 1999 planting . Annual data collection . We began collecting survival data in September , 1998 , replanted trees that did not survive ( in April , 1999 ) , and again took survival data in July , 1999 . We took â?? initial â?? TCSA at 30 cm above the ground in April , 1999 , and repeated these measurements annually , usually in November - December . In July , 1999 we also measured number of suckers , number of limb breaks , rated tree vigor ( 3 levels of vigor based on tree height ) , spreading vs upright , and terminal bud set ( see 2002 report ) . On 31 March , 2000 , we counted number of â?? truss buds â?쳌 ( 2 limbs / tree , with density calculated based on branch cross - sectional area at the base and on buds per limb length ) , bloom rating overall ( 0 = no bloom , 5 = very high bloom density ) , average number of flowers per truss bud , and number of branches per TCSA ( trunk cross - sectional area ; see 2002 report ) . We collected yield and yield efficiency data in 2001 , 2002 and 2003 . In Spring , 2002 , we visually evaluated individual trees for overall desirability , based on uniform growth habit , enough vigor with dwarfing potential for improved crop efficiency , spur development , branch strength , low root suckering , few bacterial canker symptoms . Results and Discussion : 2 Survival : Most rootstock / scion combinations had 100 % survival in 1998 , five months after planting ( Table 1 ) . Those rootstocks that showed a significant decrease in survival during this period include : W 154 ( 40 % survival ) , W 53 ( 57 % survival ) , and Mazzard ( 83 % ) . After replacing some lost trees ( mahaleb , Mazzard , Edabriz , W 53 , 154 and 158 ) in spring of 1999 , survival on 25 July , 1999 was 100 % for half of the rootstocks planted in 1998 and of those that had been replanted in 1999 , Mazzard , W 53 and W 158 maintained 100 % survival and W 154 had 88 % survival . W 72 reduced both 1998 and 1999 populations to 75 % . In 2001 , rootstocks that showed losses included Mazzard ( 11 % death , calculated as percentage of those trees surviving in 2000 ) , Weiroot 10 ( 12 % ) , W72 ( 50 % ) , W154 ( 20 % ) and Colt ( 67 % ) . In 2002 , losses tended to occur with rootstocks that had shown declines in 2001 , in addition to a few that showed new losses since 2000 . These included : Mazzard ( 41 % loss ) , mahaleb ( 12 % ) , Giessen 473 - 10 ( 50 % ) , Edabriz ( 14 % ) , W 10 ( 11 % ) , W13 ( 13 % ) , W53 ( 25 % ) , W72 ( 50 % ) , W158 ( 50 % ) . In 2003 few losses occurred ; these were single trees of Gi318 - 17 , Gi 473 - 10 , W10 and W154 . Based on visual evaluation of trees remaining in Spring , 2002 , we scored desirability overall ( Table 2 ) . Among these , W154 proved to be the least desirable , in addition to having the lowest survival rate overall . Vegetative growth , 1999 - 2003 : TCSA on 27 April , 1999 was highest in Gi 148 - 1 ( Table 3 ) . Rootstocks not significantly different from Gi 148 - 1 included : mahaleb , Gi 148 - 2 , Gi 148 - 8 , Gi 195 - 20 , Gi 209 - 1 , Gi 318 - 17 and W 13 . W 154 showed the least TCSA and the remaining rootstocks were not significantly different from it . In 2000 the same rootstocks were the most vigorous among those planted in 1998 , and many of those that had been statistically equivalent to the leaders in 1999 were now significantly less vigorous . Among those planted in 1999 , rootstocks â?? Colt â?? and Mazzard were the most vigorous , with most others statistically similar and W53 significantly lower in growth than the 2 leaders ( but similar to the mid - range rootstocks ) . In 2001 there was no significant difference among rootstocks with respect to growth in those planted in 1998 , although there was considerable difference numerically . The range of sizes within most rootstocks was such that the variability found in most of the rootstocks was too great to determine statistical differences . Among those rootstocks planted in 1999 , W154 showed the greatest growth and all others were statistically less vigorous , but equivalent amongst the lower - range group . Overall , the greatest growth has been in Colt , followed by Standard mahaleb . Of the remaining rootstocks , Gi 148 - 1 , 318 - 17 , W13 and W154 have shown the greatest increase in TCSA . Substantially less vigor was found in Gi 148 - 2 , 148 - 8 , 209 - 1 , 473 - 10 , Edabriz , and the majority of the Weiroot group . Bloom density and Productivity ( Tables 3 and 4 ) : Flower abundance and full bloom : Flower abundance is an expression of the density of bloom open at a given time , closest to full bloom , so as to evaluate how many flowers are physically present on the tree and are open simultaneously . Earlier in the bloom cycle , abundance may evaluate the number of spurs present along a scaffold limb . In March of 2000 , bloom abundance on a whole tree basis was highest in Gi 209 - 1 and 195 - 20 for trees planted in 1998 ; of those planted in 1999 , the strongest bloomer was Edabriz . Mazzard was the lowest in flower abundance . On March 25 , 2001 , of trees planted in 1998 , Mazzard was again , the lowest bloomer with W154 and W13equivalent . Gi 148 - 2 , 209 - 1 and 195 - 20 were , again , high bloomers . Trees planted in 1999 showed no significant differences in bloom density . Full bloom date for trees in 2001 ( both ages combined ) , was equivalent in all but 148 - 8 , which bloomed earliest , and W72 , which bloomed latest . Statistically significant differences were only apparent between these 2 rootstocks . Flower abundance in March , 2002 , was highest to date , with most rootstocks showing 30 % or more of the tree volume filled . Highest bloomers included mahaleb , 148 - 2 , 473 - 10 and Colt . Lowest bloomers were Mazzard , 148 - 8 , 318 - 17 , Edabriz , W53 , and lowest were W158 and W10 ( virtually no flowers ) . Most rootstocks conferred bloom timing that was at full bloom or petal fall by 28 March , 2002 . Those that were significantly late included mahaleb , Gi 148 - 1 , Edabriz and W154 . Fruit production ( Table 3 ) was very low in 2002 and 2003 as low chill conditions prevailed in those dormant seasons . . Cropping had only just begun to show productivity . Overall , rootstock tends to have a significant to highly significant effect on the parameters of performance 3 represented by the data gathered . In future years we expect to continue to measure vegetative and reproductive vigor , fruit set , yield , fruit size and quality , cropping efficiency , presence of blind wood , early senescence , disease susceptibility , uniformity of growth habit and size , and any other horticultural characteristics that appear to be important . 4 Table 1 . Cherry rootstocks tested for NC140 Regional cherry project ; survival . Z % Survival 7 / 25 / 99 4 / 31 / 00 Y 11 / 01 10 / 02 6 / 03 Trees planted in 9 / 98 Rootstock Species or hybrid 1998 1999 1998 1999 Mazzard Prunus avium 83b 100a 83b 100a 89a 59bc 59bc X 83b mahaleb P . mahaleb 88ab 100a 88ab 100a 100a 88ab 88ab 88ab Giessen ( Gi ) 148 - 1 100a 100a 100a 100a 100a 100a P . cerasus x P . canescens 148 - 2 100a 100a 100a 100a 100a 100a ( Germany ) 148 - 8 100a 100a 100a 100a 100a 100a 195 - 20 100a 100a 100a 100a 100a 100a 209 - 1 88ab 88ab 100a 100a 100a P . canescens x P . 88ab cerasus 318 - 17 100a 100a 100a 100a 100a 88ab 473 - 10 100a 50b 50b 100a 100a 97ab P . cerasus ( Iran , INRA Edabriz ( Tabel ) 100a 100a 100a 100a 100a 100a 86ab 86ab France ) Weiroot ( W ) 10 100a 100a 100a 88a 88ab 82ab W 13 100a 88b 88b 100a 100 100a W 53 57bc 100a 57b 100a 100a 75ab 75ab 57bc P . cerasus ( Germany ) W 72 100a 75b 75a 75ab 75b 50b 25c 25cd W 154 40c 40c 100a 40c 83b 80ab 30c 15d W 158 100a 100a 100a 100a 100a 100a 50bc 50bc Colt 100a 100a 33c 33c 33c X Mean separation within columns by Duncanâ??s multiple range test , P = 0.05 . Y Survival in 2001and subsequent years was calculated as percentage of trees that survived in 2000 . Z Rootstocks were budded to â?? Bing â?? and planted 27 April , 1998 ; some trees that died in 1998 through spring , 1999 were replanted with the same rootstock . Survival in 1999 and subsequent years represents , therefore a survival figure for both original trees and replants , where applicable . 5 Table 2 . Cherry rootstocks tested for NC140 Regional cherry project ; overall evaluation , Spring , 2002 . X Rootstock Species or hybrid ( source ) Percentage of trees considered desirable Mazzard Prunus avium 100 mahaleb P . mahaleb 62 Giessen ( Gi ) 148 - 1 75 P . cerasus x P . canescens ( Germany ) 148 - 2 62 148 - 8 83 195 - 20 83 209 - 1 75 P . canescens x P . cerasus 318 - 17 80 473 - 10 100 Edabriz ( Tabel ) P . cerasus ( Iran , INRA France ) 77 Weiroot ( W ) 10 75 W 13 67 W 53 100 P . cerasus ( Germany ) W 72 100 W 154 25 W 158 100 Colt 67 X Of trees surviving in spring , 2002 , percentage of surviving evaluated as desirable overall , based on uniform growth habit , enough vigor with dwarfing potential for improved crop efficiency , spur development , branch strength , low root suckering , few bacterial canker symptoms . 6 12 / 12 / 02 2001 - 2003 bcd bcd d - g d - g d - g d - f d - g b - e efg c - f d - g bc bc fg g a b 66.5 78.6 80.2 83.5 83.8 90.4 152.8 98.6 47.7 256.0 59.1 147.1 134.8 137.8 120.8 159.8 78.0 TCSA yield total 1998 - 2000 ; Planted1999 bc b a b b b b 75.4 29.1 90.6 39.4 55.2 60.2 68.3 11 / 20 / 01 from ) 2 TCSA cm 1998 n.s . ( TCSA , 65.0 61.3 77.2 43.8 82.6 77.6 92.0 44.1 69.6 43.0 85.6 52.9 83.6 63.6 61.6 89.9 Planted significant . area cross - sectional Planted1999 non bc a a cd cd d 13.2 13.2 5.6 3.7 7.2 5.3 = n.s . column . 11 / 8 / 00 0.05 trunk the = TCSA 1998 project ; P test ; in bcd bcd bcd abc abc a - d cd cd cd ab cd cd represented d d d a Planted range 15.6 19.6 18.4 25.0 18.7 21.4 16.1 12.8 19.3 28.4 13.2 11.9 23.6 30.7 18.4 15.1 cherry multiple Regional growth Y ( 1998 ) Duncanâ??s vegetative NC140 4 / 27 / 99 X bcd bcd abc abc abc abc abc abc by cd cd cd ab cd cd for a d of columns 4.7 5.8 8.6 6.6 6.3 6.6 6.0 2.2 3.5 2.4 4.2 4.0 7.0 6.1 2.9 3.2 TCSA tested year the rootstocks within = 148 - 1 parentheses separation ( Gi100 ) 10 Cherry ( W ) 195 - 20 318 - 17 473 - 10 Rootstock in 148 - 2 148 - 8 209 - 1 3 . Mazzard Weiroot mahaleb Edabriz Giessen Mean Year 154 158 Table 53 72 13 Colt Gi Gi Gi Gi Gi Gi W W W W W X Y Table 4 . Rootstock effect on abundance of flowering and bloom date . Flower abundance on whole tree basis Z Y 3 / 31 / 00 3 / 25 / 01 Full bloom % Full Trees planted in date , March bloom , 3 / 28 / 02 , all Rootstock 2001 3 / 28 / 02 trees 1998 1999 1998 1999 X Mazzard 0.4 f 0.2e 0.3 a 2.8 bc 27 a 80 ab mahaleb 1.3 c - f 1.3cd 0 a 4.2 ab 25 ab 50 b Giessen ( Gi ) 148 - 1 2.3 abc 1.8bcd 3.8 b 25 ab 35 b Gi 148 - 2 1.8 b - e 2.9 a 4.1 ab 26 ab 85 ab Gi 148 - 8 0.9 ef 1.6bcd 2.7 bc 24 b 85 ab Gi 195 - 20 2.8 ab 2.2abc 3.4 b 26 ab 80 ab Gi 209 - 1 3.2 a 2.8 a 3.6 b 26 ab 70 ab Gi 318 - 17 1.1 def 1.2 cd 2.4 bc 25 ab 90 ab Gi 473 - 10 1.2 c - f 2.5 ab 4.6 a 26 ab 85 ab Edabriz 1.5 cde 2.6a 2.0 a - d 1.1 a 2.6 bc 26 ab 45 b Weiroot ( W ) 10 2.2 a - d 1.4 cd 0.4 d 26 ab 100 a W 13 1.3 c - f 1.0 de 3.1 b 27 a 80 ab W 53 1.4 c - f 2.0 a - d 0 a 2.5 bc 27 a 90 ab W 72 1.2 c - f 1.2 cd 3.5 b 27 a 50 b W 154 1.0 ef 1.0b 1.0 de 1.0 a 3.6 b 25 ab 70 ab W 158 1.2 c - f 0.8b 1.2 cd 1.0 a 1.3 cd 25 ab 90 ab Colt 0c 0 a 4.0 ab 26 ab 80 ab X Mean separation within columns by Tukeyâ??s test , P = 0.05 . Y Flower abundance in 2001 rated as : 0 = no bloom , 1 = 10 % of the tree volume blooming , 2 = 20 % , . . . , 5 = very dense bloom . Z Flower abundance in 2000 rated as : # clusters / 30 cm of branch : 0 = no flowers , 1 = 1 - 5 clusters , 2 = 6 - 10 , 3 = 11 - 20 . 8