Main topics of the research-project FuE 03OE088 of “Bundesprogramm Ökologischer

Landbau” (30.04.2004-31.12.2006) were the testing of foliar fertilizers in organic apples

and pears, optimizing lime sulphur for blossom thinning, looking for alternatives to lime

sulphur for blossom thinning and looking at different combinations of thinning measures.

Only the results of testing foliar fertilizers (carried out by KoGa Ahrweiler and OVB/ÖON

Jork) and combinations of thinning measures (carried out by LVWO Weinsberg) are

described in this article. Over three years only a small increase in yield was evaluated for

the fertilizers Aminosol PS and Wuxal Ascofol (site Ahrweiler, apple variety ‘Elstar’). In

Jork (apple variety ‘Holsteiner Cox’) yield could only be judged in 2005 and 2006. Wuxal

Ascofol showed some advantage in comparison to the control. At pear variety ‘Conference’

no clear tendencies could be seen, the control had the highest yield. In 2005 the fruitsetting

of ‘Conference’ was very low because of bad conditions during blossom

Eis, B.

Fieger-Metag, N.

Pfeiffer, B.

Zimmer, J.

English

Organic Eprints

324Optimizing crop loading of apples and pears -results 2004-2006 (foliar fertilizers, thinning) B. Pfeiffer1, B. Eis1, J. Zimmer2, N. Fieger-Metag3AbstractMain  topics  of  the  research-project  FuE  03OE088  of  “Bundesprogramm  Ökologischer Landbau” (30.04.2004-31.12.2006) were the testing of foliar fertilizers in organic apples and pears, optimizing lime sulphur for blossom thinning, looking for alternatives  to lime sulphur for blossom thinning and looking at different combinations of thinning measures. Only the results of testing foliar fertilizers (carried out by KoGa Ahrweiler and OVB/ÖON Jork)  and  combinations  of  thinning  measures  (carried  out  by  LVWO  Weinsberg)  are described in this article. Over three years only a small  increase in yield was evaluated for the fertilizers Aminosol PS and Wuxal Ascofol (site Ahrweiler, apple variety ‘Elstar’). In Jork (apple variety ‘Holsteiner Cox’) yield could only be judged in 2005 and 2006. Wuxal Ascofol showed some advantage in comparison to the control. At pear variety ‘Conference’ no clear tendencies could be seen, the control had the highest yield. In 2005 the fruit-setting of ‘Conference’ was very low because of bad conditions during blossom.  All combinations, which consisted of two thinning measures, balanced the crop loading of ‘Elstar’ (organic orchard near LVWO Weinsberg) in a way, that in spring 2007 the setting of blossom clusters was clearly higher than in the control, so alternate bearing could be reduced. The best effects had thinning strategies, that included blossom thinning (2 x 30 l/ha lime sulphur). Less time was necessary for thinning by hand, when additional pruning was done (169 h/ha thinning by hand - only by hand 255 h/ha) or when blossom spraying  was performed (101 h/ha left for thinning by hand).Keywords: thinning, foliar fertilizers, apples, pears, organic orchards IntroductionIn  spring  2004  a  research  project  granted  by  the  “Bundesprogramm  Ökologischer Landbau” (FuE 03OE088) started with the aim to test different possibilities  to increase fruit setting  of  apples  and  pears  by  using  foliar  fertilizers  on  one  hand  and  to  reduce  an overloading crop  on alternate bearing apple varieties by additional pruning in spring or by blossom  sprayings  on  the  other.  The  selection  of  the  tested  foliar  fertilizers  based  on  results  from  Renner  (2002),  Ruess  &  Belz  (2003)  and  on  experiences  of  organic  fruit growers.  Within  blossom  thinning  different  application  doses  of  lime  sulphur  (variety ‘Elstar’) and possible alternatives to lime sulphur were tested at the varieties ‘Gala‘ or ‘Elstar’. The results of this trials were described detailed in the final research-report (Eis & Pfeiffer, 2008). In the following the most important results of the foliar fertilizer experiment and of a trial about combinations of different thinning measures shall be discussed.                                                  1 Staatliche Lehr- und Versuchsanstalt für Obst- und Weinbau, D-74 189 Weinsberg, e-mail: barbara.pfeiffer@lvwo.bwl.de 2 Kompetenzzentrum Gartenbau, DLR Rheinpfalz, D-53 474 Bad Neuenahr-Ahrweiler, e-mail: juergen.zimmer@dlr.rlp.de 3 ÖON/OVB Jork, D-21 635 Jork, e-mail: Nicole.Fieger-Metag@lwk-niedersachsen.de Archived at http://orgprints.org/13741/325Optimizing crop loading of apples and pears -results 2004-2006 (foliar fertilizers, thinning) B. Pfeiffer1, B. Eis1, J. Zimmer2, N. Fieger-Metag3AbstractMain  topics  of  the  research-project  FuE  03OE088  of  “Bundesprogramm  Ökologischer Landbau” (30.04.2004-31.12.2006) were the testing of foliar fertilizers in organic apples and pears, optimizing lime sulphur for blossom thinning, looking for alternatives  to lime sulphur for blossom thinning and looking at different combinations of thinning measures. Only the results of testing foliar fertilizers (carried out by KoGa Ahrweiler and OVB/ÖON Jork)  and  combinations  of  thinning  measures  (carried  out  by  LVWO  Weinsberg)  are described in this article. Over three years only a small  increase in yield was evaluated for the fertilizers Aminosol PS and Wuxal Ascofol (site Ahrweiler, apple variety ‘Elstar’). In Jork (apple variety ‘Holsteiner Cox’) yield could only be judged in 2005 and 2006. Wuxal Ascofol showed some advantage in comparison to the control. At pear variety ‘Conference’ no clear tendencies could be seen, the control had the highest yield. In 2005 the fruit-setting of ‘Conference’ was very low because of bad conditions during blossom.  All combinations, which consisted of two thinning measures, balanced the crop loading of ‘Elstar’ (organic orchard near LVWO Weinsberg) in a way, that in spring 2007 the setting of blossom clusters was clearly higher than in the control, so alternate bearing could be reduced. The best effects had thinning strategies, that included blossom thinning (2 x 30 l/ha lime sulphur). Less time was necessary for thinning by hand, when additional pruning was done (169 h/ha thinning by hand - only by hand 255 h/ha) or when blossom spraying  was performed (101 h/ha left for thinning by hand).Keywords: thinning, foliar fertilizers, apples, pears, organic orchards IntroductionIn  spring  2004  a  research  project  granted  by  the  “Bundesprogramm  Ökologischer Landbau” (FuE 03OE088) started with the aim to test different possibilities  to increase fruit setting  of  apples  and  pears  by  using  foliar  fertilizers  on  one  hand  and  to  reduce  an overloading crop  on alternate bearing apple varieties by additional pruning in spring or by blossom  sprayings  on  the  other.  The  selection  of  the  tested  foliar  fertilizers  based  on  results  from  Renner  (2002),  Ruess  &  Belz  (2003)  and  on  experiences  of  organic  fruit growers.  Within  blossom  thinning  different  application  doses  of  lime  sulphur  (variety ‘Elstar’) and possible alternatives to lime sulphur were tested at the varieties ‘Gala‘ or ‘Elstar’. The results of this trials were described detailed in the final research-report (Eis & Pfeiffer, 2008). In the following the most important results of the foliar fertilizer experiment and of a trial about combinations of different thinning measures shall be discussed.                                                  1 Staatliche Lehr- und Versuchsanstalt für Obst- und Weinbau, D-74 189 Weinsberg, e-mail: barbara.pfeiffer@lvwo.bwl.de 2 Kompetenzzentrum Gartenbau, DLR Rheinpfalz, D-53 474 Bad Neuenahr-Ahrweiler, e-mail: juergen.zimmer@dlr.rlp.de 3 ÖON/OVB Jork, D-21 635 Jork, e-mail: Nicole.Fieger-Metag@lwk-niedersachsen.de Material and Methods Experiment  1  (foliar  fertilizers)  consisted  of  three  trials.  The  Kompetenzzentrum Gartenbau in Ahrweiler (near Bonn) tested on an organic orchard BIOFA Algenextrakt (5 l/ha), Wuxal Ascofol (3 l/ha), Aminosol PS (5l/ha), bitter salt (7 kg) and a combination of LEBOSOL Zink & LEBOSOL Mangan (varying doses depending from stage of tree) at the apple variety ‘Elstar’ and at the pear variety ‘Conference’. Each fertilizer was sprayed on 4 x 7 trees. In every year 3 applications were done around  blooming time, for the treatment Zn+Mn  one  additional  application  followed  after  harvest.  Yield  (kg/tree),  average  fruit weight,  fruit  size  grading,  percentage  of  red  colour  and  russeting  of  the  fruits  were evaluated  on apples,  on pears only yield and fruit size grading. A similar trial with the same  variants  (4  x  6  trees  per  variant)  was  carried  out  by  the  ÖON/OVB  Jork  (near Hamburg) in an organic orchard at the variety ‘Holsteiner Cox’. Here the treatment Zn+Mn was replaced with Kaliumsulfat. Because of heavy attack of Dysaphis plantaginea the yield in 2004 could not be evaluated, so data were assessed from 2005 and 2006. In experiment 2 the effect of different combinations of thinning measures on the amount of  time  needed  for  thinning  by  hand,  yield,  average  fruit  weight,  size-grading  and percentage of red colour was evaluated. The trial was carried out at over 15 years old, organic  grown  trees  of  ‘Elstar’  (10  trees  per  treatment,  each  tree  was  counted  as replication).At first trees with a high number of blossom buds were selected for the trial. At these trees the normal winter pruning was done following the remark of the farmer that winter  pruning  should  not  last  longer  than  50-60  h/ha.  Afterwards  the  first  measure  “additional  pruning”  to  reduce  the  number  of  branches  with  lots  of  blossom  buds  was carried out. For this work a limit of about 18-20 h/ha was set. Single branches and parts of the trees with lots of spurs were removed. In spring 2006 between 350 and 500 blossom clusters/tree were counted on the about 2,5 m high trees. For “Blossom thinning” lime sulphur (30 l/ha) was sprayed with a portable Solo-Sprayer (air-supported) at beginning and at full blossom. “Hand thinning” was done on May 31st 2006 before June drop, time necessary for that step was stopped for each tree separately. These three measures were combined in different ways (see table 1).Table 1: Combination of thinning measure at the variety ‘Elstar’ 2006 Treatment Abbreviation(in figures) additionalpruningblossomthinninghand thinning1  Con       2  H      X 3  add. Pr.  X     4  add. Pr.+H  X    X 5  add. Pr.+B  X  X   6  add. Pr.+B+H  X    X 7  B    X   8  B+H    X  X Archived at http://orgprints.org/13741/326The evaluations were focussed mainly on the following points: •  How much time is necessary for the different strategies •  Are there improvements in fruit-weight, size-grading and colour of the fruits? •  Which strategy has the best potential to break alternate bearing in a sufficient way? In  December  2006  the  percentage  of  blossom  and  leaf  buds  was  evaluated  under binocular (Baab, 1988) to see, if the measures had success to break alternate bearing. Finally  the  number  of  blossom  clusters/tree  were  counted  in  April  2007  to  check  the tendencies from bud-analysis. ResultsBetween the foliar fertilizers tested in experiment 1 (variety ‘Elstar’) Aminosol PS showed the highest yield with 11,58 kg/tree (average per year, data from 2004-2006). The second best  result  was  found  at  Wuxal  Ascofol  (11,71  kg/tree*year)  in  comparison  to  control variant (10,96 kg/tree*year). The other treatments had the same level as the control or a little bit lower (Eis, Pfeiffer, Zimmer & Fieger-Metag, 2008). Treatments with a high total yield had also the most apples in size 65-85 mm. Some fruits showed more russeting, but it was not clear, if there were interactions with the plant protecting strategy against scab. Under the conditions in Northern Germany only the foliar fertilizer Wuxal Ascofol (22,6 kg/tree  and  year,  average  from  2005+2006)  increased  the  yield  of  ‘Holsteiner  Cox’  in comparison to control (20,3 kg/tree*year). The average fruit weight mainly was influenced by the intensity of crop loading of each treatment. In the field trial with the pear variety ‘Conference’ in the year 2005 yield was very low because of bad weather conditions during pear blossom time (less than 1,5 kg/tree). The total yield (average from years 2004-2006) was  highest in the control (10,13 kg/tree*year), followed  closely  by  the  other  variants  except  for  bitter  salt  (only  8,3  kg/tree*year),  the reason for that bad result was not clear. Size grading was very similar within all variants with the highest peak in size 65-70 mm. In experiment 2 (combining of thinning measures) the fruit setting on the control-trees at the end of May was about 1 apple/blossom cluster, in the treatments with hand thinning the fruit setting was reduced to 0,6 apples/blossom cluster. During summer even in the not thinned control many fruits dropped down because of cold temperature in the night and less bees flying during blossom, so at harvest only 0,2-0,3 apples/cluster were counted at trees without hand thinning. Figure 1 shows the requisite time (hours/ha) for different thinning strategies (except for 2,5 h/ha for thinning spraying at blossom) in view of the following facts: •  in this orchard about 1900 trees/ha were planted, the trees were very vigorous •  As result of assessments of flowering intensity in alternate bearing varieties it was assumed, that only 70 % of the trees per ha  have so much blossoms, that strong thinning measures like the tested ones are necessary Archived at http://orgprints.org/13741/327Lots of hours were necessary at the trees, where thinning was done only by hand. In some treatments (add. Pr., add. Pr.+B, B) no apples were thinned by hand. Additional pruning lasted  only  12-16  h/ha  and  reduced  time  for  thinning  by  hand  to  170  h/ha.  At  the combination  “additional  pruning  +  blossom  thinning”  only  about  100  h/ha  were  left  for thinning by hand. The combination “additional pruning + blossom thinning + hand “ had the lowest requisite time in the measure “thinning by hand” (65 h/ha). During summer natural fruit drop was relatively high, so finally at harvest this strategy had thinned too heavy (see data about total yield). Requisite time (h/ha) for combinations of different thinning measures at 'Elstar' 050100150200250300350Con H add.Pr.+H add.Pr.+B+H B+H add.Pr. add.Pr+B Bh/ha (70 % heavy flowering trees) normal pruning additional pruning thnining by handa ababcddbcab abFigure  1:  requisite  time  (h/ha)  for  combinations  of  different  thinning  measures  at  ‘Elstar’,  for variants with “B” about 2,5 h/ha must be added for blossom sprayings, control without any thinning, Tukey-test, α= 0,05 for total requisite time In the not thinned control about 190 apples/tree were left in autumn, at the first picking in all variants about 6-7 kg/tree were harvested. How many apples were harvested at the second and the third time was influenced by the success of thinning strategy (See table 2). The average fruit weight in the control was 150 g. All apples of 10 trees per treatment were sorted with an AWETA size-grading machine as one unit. Figure 2 shows the total yield per tree, divided in three grades (excellent coloured + good size, well coloured + good size, green + small). As expected the highest yield was evaluated for the not thinned control, but 5,72 kg/tree were too green or too small. In this organic orchard the plant density was about 1900 trees/ha, so between 15 and 20 kg unsorted apples/tree still met 28,5 to 38 t/ha. By the different  thinning  strategies  the  part  of  the  lowest  quality  grade  (too  small  and  green) decreased.  Archived at http://orgprints.org/13741/328Table 2: total yield, kg, 2nd and 3rd picking, average fruit weight ,g, (significances following tukey-test, α = 0,05), % flower-buds in December 2006 Variant total yield kg/tree2nd picking kg/tree3rd pickingkg/treeaverage fruit weight (g) % flower-buds Dec. 06 Con 28,72  7,93  13,52  155    ab  31 H 26,80  9,05  10,66  146    a  34 add. Pr.  18,33  8,43  4,36  162    ab  53add. Pr.+H  19,92  6,54  7,27  170    b  55add. Pr.+B  14,08  5,02  2,32 157    ab  51add. Pr.+B+H  9,72  2,87  2,78 150    a  67 B 19,11  6,52  6,38  153    ab  49B+H 19,30  6,43  5,16  154    ab  52Quality grades at 'Elstar' as reaction oncombinations of thinning measures 2006051015202530Con Hand add.Pr add.Pr+H add.Pr+B add.Pr+B+H B B+Hkg/tree 2006kg65-90/F4+F5 kg65-90/F2+F3 kg<65/F1/>90Figure 2: Total yield (kg/tree) of ‘Elstar’ 2006, divided in three quality grades (small + green, well coloured + good size, excellent coloured + good size), plant density 1900 trees/ha. Bud-analysis in December 2006 allowed a good forecasting of flowering-intensity in spring 2007 as shown in figure 3. Hand thinning had less success in breaking alternate bearing, even if it was done early, and showed a large variation. Additional pruning as a simple measure had some effects. If a fruit-grower is not allowed or is not willing to use lime sulfur for blossom thinning, this might be a possible solution. Clearly all combinations including blossom thinning with lime sulfur (2 x 30 l/ha) had the strongest effect on alternate bearing. These trees had about 180 to 225 blossom-clusters more than the control in spring 2007.  Archived at http://orgprints.org/13741/329Blossom-cluster/tree 2007 at 'Elstar' after combination of thinning measures 20060100200300400500BB 2007 194 240 303 251 378 420 385 409Con H add.Pr.add.Pr.+Hadd.Pr.+Badd.Pr.+B+HB B+HFigure 3: Number of blossom-cluster/tree in 2007 at ‘Elstar’ after thinning measures 2006 (Tukey-test, α = 0,05) Summary experiment 2 Blossom thinning and additional pruning had success in reducing time needed for thinning by hand, the yield was lower than in control (about 7 kg/tree less in acceptable quality) and less too small and green apples were harvested. This lower yield was compensated by a higher setting of blossom clusters in the next spring 2007, which led to an estimated higher yield of about 10 kg/tree (180 blossom-clusters more per tree x 0,4 apples/cluster x 140 g/apple), while the yield of the not thinned trees of the control was low. The aim of partly reducing alternate bearing could be reached in this trial. Even one year later the trees with additional pruning showed a clear difference in the growing characteristics (better balance between crop loading and growth increment). Acknowledgements We  want  to  thank  all  organic  fruit-growers  allowing  us  to  do  experiments  about  foliar fertilizers and thinning measures in their orchards and the BLE for the financial support within the “Bundesprogramm Ökologischer Landbau”.References Baab, G. (1988): Zweijährige Erfahrungen mit der Knospenanalyse, OBSTBAU 10/1988, 460-469. Eis, B.; Pfeiffer, B.; Zimmer, J.; Fieger-Metag, N. (2008): Untersuchungen zur Optimierung der Behangsdichte  im  ökologischen  Kernobstanbau.  Abschlußbericht  Forschungsprojekt  Nr. 03OE088, Bundesprogramm Ökologischer Landbau. Renner, U.; Helm, H.-U. (2002): Blattdünger im ökologischen Apfelanbau, Mitteilungen 01/2002 des Beratungsdienstes Ökologischer Obstbau e. V. an der LVWO Weinsberg, 12-14. Ruess,  F.;  Belz,  J.  (2003):  Untersuchungen  zum  Einsatz  von  Blattdüngern  im  Ökologischen Obstbau - Status Quo Analyse und  Prüfung von Blattdüngern. Abschlußbericht abaabc abbc c bc bcArchived at http://orgprints.org/13741/

Optimizing crop loading of apples and pears - results 2004-2006 (foliar fertilizers, thinning)

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