In 2002 an experiment about thinning blossoms of the apple variety 'Pinova' lime sulfur (in 2002 45

% thinning) and sodium salt (21 % thinning) showed good effects, the number of blossom-clusters

in 2003 was very high in the lime sulfur parcels. Results from extracts of Hericium erinaceum in

2003 have to be replicated again, the number of applications must be increased

Englert, M.

Pfeiffer, B.

English

Organic Eprints

1 LVWO Weinsberg, Traubenplatz 5, D-74189 Weinsberg Results from thinning experiments in 2002 and 2003 Ergebnisse aus Ausdünnungsversuchen in den Jahren 2002 und 2003 Pfeiffer B.1, Englert, M.1 Abstract In 2002 an experiment about thinning blossoms of the apple variety 'Pinova' lime sulfur (in 2002 45 % thinning) and sodium salt (21 % thinning) showed good effects, the number of blossom-clusters in 2003 was very high in the lime sulfur parcels. Results from extracts of Hericium erinaceum in 2003 have to be replicated again, the number of applications must be increased. Keywords:  Apple,  organic  fruit-growing,  thinning  of  blossoms,  lime  sulfur,  sodium  salt, potassium chloride Introduction: An important goal of organic fruit-growers is the regulation of yield to avoid alternate bearing, which is typical for some varieties like 'Elstar' or 'GoldRush'. Other varieties like 'Gala', 'Rubinette' or 'Pi-nova' tend to bear too much and too small fruits. Too heavy fruit setting also has negative effects on the inner quality and on the initiation of flower buds for the next season. In the past good effects were produced by the application of lime sulfur, this treatment was used as a standard. The effect of lime sulfur was not the same every year, depending from the weather conditions. Some satisfac-tory thinning effects were achieved in 2001 by the application of sodium salt (see literature cited). Material and Methods: During the master education at the LVWO Weinsberg M. Englert (2002) made an experiment about blossom thinning with different agents for the ecological fruit-growing. The trial took place on the fruit experimental station Heuchlingen near to Heilbronn in a conventionally managed orchard with very homogeneous trees of the variety 'Pinova'. The trees were planted in 1994 (distance 3,50 m x 1m) and were about 2,50 m high. Per treatment 10 trees with a high number of blossom clusters were chosen. The number of clusters on the whole tree was counted. In the season 2002 (experi-ment  1)  the  complete  rows  were  sprayed  with  a  Joco-tunnel-sprayer  with  1000  l  per  ha  water amount. Basing on the results of Ruess and Pfeiffer (2002) for sodium salt and potassium chloride an amount of 10 kg salt per ha was chosen. The treatments are listed in table 1. In the figures the following abbreviations will be used: B= beginning blossom (BBCH 61), F= full blossom (BBCH 65).  Table 1: Thinning treatments during blossom 2002 at variety 'Pinova' (experiment 1)  Treatment 2002  per ha  first treatment  second treatment Control (Con)    untreated  untreated Sodium salt (KS)  10 kg/ha  beginning blossom   Sodium salt (KS)  10 kg/ha  beginning blossom  full blossom Sodium salt (KS)  10 kg/ha    full blossom Potassium chloride (KCl)  10 kg/ha  beginning blossom  full blossom Lime sulfur (SK)  30 l/ha    full blossom Thinning by hand (H)    June 28th 2002 thinning of bad fruit qualities  (not for breaking alternate bearing) Archived at http://orgprints.org/14530/  The first time the agents were applied in the morning of April 18th 2002, the sky was clouded, tem-perature of air was only 7 to 10 ° C, the relative h umidity of air was high with 85 to 90 %. Leave moisture was low.. The second treatment followed on April 22nd at lunchtime. It was warm (20 ° C) and sunny, relative air humidity was low at 42 %, the sky was only a little bit cloudy. The weather during blossom 2002 was mainly cold and wet, some blossoms had been damaged by cold temperatures in early spring, so the fruit-setting was not so high. The fruit setting was evalu-ated twice (before june-fall and at harvest), the number of apples per tree was counted. The thin-ning effect (in %) for lime sulfur e.g. was calculated in comparison to control: (1-(apples per 100 clusters lime sulfur / apples per 100 clusters control))*100. A negative value means, that the fruit setting was higher than in control.  At harvest each tree was picked separately for the calibration of size and colour with an AWETA-sorting-machine. Size was classified in 5 mm grades, colour in 5 classes. A randomised sample of 100 fruits per treatment was evaluated on russeting (4 classes) to get an estimation of russeting potential of the thinning application.   The influence on the blossom 2003 was investigated twice: In January 2003 a mixed sample of 75 buds per treatment (one twig per tree was removed) was analysed under microscope, the buds were divided in leaf- and blossom-buds. In April 2003 the number of blossom clusters per tree was counted again.   In spring 2003 the following thinning experiment (experiment 2) was started, some of the treat-ments were tested on their thinning effect because they seemed to be interesting for protection of apple scab. Only one application was done in the morning of April 23rd at full blossom (BBCH 65), the weather was a bit foggy with dew on the leaves, temperature was about 7 to 10 ° C, relative hu-midity of air was 96 to 100 %. The agents were sprayed with portable sprayer (420 ml per tree). As treatments were chosen with the amounts per ha: Control (untreated), Quillaja-Saponin 7,5 kg, Quil-laja-saponin + sulfur (7,5 kg / 2 kg), Lime sulfur (30 l), sodium salt (8 and 10 kg), Agromil (2,5 kg), an extract of Asian mushroom (10 kg extract from Hericium erinaceum) and sunflower-oil (26 l, for-mulated with 4 l RIMULGAN).Sodium salt 10 kg was part of the conventional trial, sprayed with Joco-tunnel-sprayer. All evaluations were done in the same kind as in experiment 1.  Results experiment 1 (2002): Per tree between 200 and 246 clusters were counted, the average over the whole trial was 228. Figure 1 shows the thinning effect of the treatments during blossom, the values are calculated from the number of apples per cluster on May 15th 2002. With lime sulfur application during full blossom a thinning effect of about 45 % was achieved, this was nearly too strong. Comparing only the so-dium salt treatments the second treatment at full blossom had more efficiency than that at the be-ginning of flowering, one reason could be the cold weather during the first treatment. The thinning effect of the second treatment was about 22 %. The two spraying of potassium chloride caused about 32 % thinning effect.  Archived at http://orgprints.org/14530/  -1001020304050KS B KS F KS B+F KCl B+F LS F% Figure 1: % thinning effect of KS=sodium salt, KCL=potassium chloride, LS=lime sulfur  Dates from harvest 2002 are summarized in table 2, all values are the average from 10 separately evaluated trees. In the last column the fruit-setting per cluster at harvest is listed.  Table 2: Yield per tree (kg), average fruit weight (g) and fruit setting at harvest (apples per blossom cluster) at 'Pinova' 2002 Treatment (date)  kg/tree  Fruitweight (g)  Apples per cluster at harvest Control  15,07  125  0,60 Sodium Salt (B)*  23,35  158  0,60 Sodium Salt (F)*  18,06  143  0,53 Sodium Salt (B+F)*  19,86  150  0,59 Potassium chloride (B+F)*  18,83  148  0,45 Lime sulfur (F)*  17,82  168  0,46 Thinning by hand  14,88  170  0,41 * B=begin of blossom, F=full blossom  There were some fluctuations between the different treatments at the yield per tree (15 kg per tree in control versus 23 kg in sodium salt (B)). In the control the average weight per apple was very low, because the most apples had a size between 65 and 75 mm. By thinning by hand quite a few ap-ples were removed from the trees because of lacks in quality (size, less colour). So weight per apple was very high with 170 g, but the yield per tree with about 15 kg was as low as in control. The time for picking the apples was reduced clearly. The best relation between yield per tree and fruit weight was seen at lime sulfur treatment. In figure 2 the distribution of the yield (as kg/tree) in the different classes of size is compared.  In all treatments a shifting towards higher diameter of the apples could be watched, the most clearly at lime sulfur and thinning by hand, between these two variants was nearly no difference. Principally the russeting of the apples was low, fruits in the categories 3 (10-30 % russeted skin) and 4 (> 30 % russeted skin) were watched seldom. Between the treatments nearly no differences were seen. Fi-nally the results about blossom 2003 are listed in table 3.  Archived at http://orgprints.org/14530/                Figure 2: kg/tree in classes < 60 mm up to > 90 mm, comparison of control (Con), lime sulfur (SK F), sodium salt (KS B+F) and thinning by hand (Hand)  Table 3: % leaf- and flower buds January 2003 before pruning, blossom cluster/tree April 2003 Treatment April 2002  % leaf-buds Jan. 2003 % weak flower buds Jan. 2003 % strong flower buds Jan. 2003 blossom-clusters/tree April 2003 Control  28,0  58,7  13,3  213 Sodium Salt (B)*  18,7  61,3  20,0  179 Sodium Salt (F)*  18,7  54,6  26,7  219 Sodium Salt (B+F)*  9,3  49,3  41,3  198 Potassium chloride (B+F)*  6,7  41,3  52,0  220 Lime sulfur (F)*  2,7  54,6  42,7  306 Thinning by hand  2,7  54,7  42,6  215 * B=begin of blossom, F=full blossom  A high percentage of strong flower-buds was counted under the microscope in the treatments so-dium salt (B+F), potassium chloride (B+F), lime sulfur (F) and thinning by hand. In the control the lowest percentage of flower-buds was evaluated. These results could be confirmed with the count-ing of blossom-clusters in April 2003. Lime sulfur had the most blossom clusters with 306 clusters per tree. On the other side in the control only 213 clusters per tree were counted. Results experiment 2 (2003): In the season 2003 there were some cold nights in April, so about 70 % of the flowers had been damaged before blossom. Only small differences were watched between the treatments, the yield per tree was homogeneous, the weight of the fruit fluctuated weakly. Altogether the average fruit weight was very low because of 2 weeks extremely hot and dry weather in August 2003. None of the treatments increased the russeting of the fruits severely. The results are listed in table 4. The percentage of leaf- and flower-buds will be counted in February 2003, the number of clusters/tree in April 2003. 012345678<60 60-65 65-70 70-75 75-80 80-85 85-90 >90mmkg/tree KS B+FHandLS FConArchived at http://orgprints.org/14530/   Table 4: Flower-clusters/tree, fruit-setting before june-fall (apples per flower cluster), yield (kg/tree), average fruit weight (g) and fruit-setting at harvest, variety 'Pinova' 2003 Treatment  Clusters/tree  Fruit-setting be-fore june-fall kg/tree  Weight/apple g  Fruit-setting at harvest Control  333  0,80  21,68  87  0,75 Quillaja-saponin  223  1,07  22,64  99  1,05 Quillaja.-Saponin            + sulphur 240  0,89  21,04  96  0,94 Lime sulfur  256  0,85  23,87  98  0,96 Sodium salt 0,8%  243  0,84  20,21  88  0,96 Sodium salt 1,0 %*  334  0,87  29,29  91  1,01 AGROMIL  245  0,96  20,40  85  1,01 Hericium erinaceum  238  0,94  23,09  98  1,01 Sunflower oil  231  0,95  22,08  97  1,03 * for comparison from conventional trial  The highest percentage of well coloured apples with diameter between 65 and 90 mm were evalu-ated at the treatments with lime sulfur, sunflower-oil and the Asiatic mushroom Hericium erinaceum. Discussion: In 2002 the use of sodium salt with 10 kg/ha at full blossom showed good effects, it was nearly as effective as lime sulfur (30l/ha), when it was applicated during warm weather. In the following sea-son lime sulfur had the highest setting of flower buds. The results could not be affirmed in 2003, but it seemed to be a specific situation in 2003 because of the dry spring and dry summer. In conven-tional thinning trials in Southern Germany the effects were low, too. Some thinning effects were caused by an extract from Hericium erinaceum, these results have to be replicated the next years, the number of treatments should be increased. In Germany it is necessary to achieve a registration of some agents for thinning blossoms in ecological apple production.  Literature Cited: Bloksma, Joke, Jansonius, Pieter Jans (2001): Bloemdunen met Kalkzwavel - Drachtregulatie in de biologische fruitteelt, deel 2, Driebergen  Englert, Martina (2002): Ausdünnung im ökologischen Obstbau, Sommerarbeit während Obstbau-Meisterausbildung an der LVWO Weinsberg. Pfeiffer, Barbara, Rueß, Franz(2002): Screening of agents for thinning blossoms of apple trees; in: Proceedings of the 10th International Conference on Cultivation Technique and Phytopa-thological Problems in Organic Fruit-Growing and Viticulture 2002, Seite106-111. Internet pages: http//:www.ffcr.or.jp/zaidan/FFCHROME.nsf/pages/ffij-e175-10.pdf  Mizuno, Takashi: Bioactive Substances in YAMABUSHITAKE, the Hericium erinaceum fungus, and its Medizinal Utilization (24.Okt.2003) Archived at http://orgprints.org/14530/

Results from thinning experiments in 2002 and 2003

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