Different strawberry varieties, available from organic propagation at that time were, planted

in August 2004 and proofed about their suitability for organic cultivation, each variety was

tested with and without biodegradable mulch film. Within the early ripening strawberry

varieties ‘Clery’ had a middle yield and was susceptible for infections with leaf spot, losses

of plants by Verticillium were seldom. This variety should be planted early to reach enough

vigor in autumn. ‘Clery’ has an interesting potential in the phase of higher prices at the

beginning strawberry season. ‘Darselect’ ripened shortly before ‘Elsanta’, the yield was

lower, but the fruit-size bigger, so the picking could be done more quickly. ‘Elsanta’

showed in this trial under organic conditions not too bad results, but on this area no

strawberries had been cultivated for many years before, so the potential of soil-borne

diseases was only low to middle.

In the group of middle ripening varieties ‘Korona’ suffered under the hot weather in June

2006 and reacted with heavy wilting symptoms, first of all caused by Verticillium, and with

more leathery and small fruits. ‘Florence’ and ‘Peco’ had often sunburst (by intensive

sunbeams). ‘St. Pierre’ had a vigor plant, middle yield and less sunburst, but should be

picked well ripened. The late variety ‘Yamaska’ was robust, but tasted only middle good.

The biodegradable mulch film increased in the first year the yield of the early ripening

varieties, in the second year with a hot summer this effect disappeared. Partly snails used

the mulch film as refuge, damages of the film also were caused by birds. The natural

decomposition was sufficient, when the film was tilled into the soil after the second

harvest

Pfeiffer, B.

English

Organic Eprints

133 Testing of strawberry-varieties (with/without biodegradable mulch film) for organic cultivation B. Pfeiffer 1AbstractDifferent strawberry varieties, available from organic propagation at that time were, planted in August 2004 and proofed about their suitability for organic cultivation, each variety was tested  with  and  without  biodegradable  mulch  film.  Within  the  early  ripening  strawberry varieties ‘Clery’ had a middle yield and was susceptible for infections with leaf spot, losses of plants by Verticillium were seldom. This variety should be planted early to reach enough vigor in autumn. ‘Clery’ has an interesting potential in the phase of higher prices at the beginning strawberry season. ‘Darselect’ ripened shortly before ‘Elsanta’, the yield was lower,  but  the  fruit-size  bigger,  so  the  picking  could  be  done  more  quickly.  ‘Elsanta’ showed  in  this  trial  under  organic  conditions  not  too  bad  results,  but  on  this  area  no strawberries  had  been  cultivated  for  many  years  before,  so  the  potential  of  soil-borne diseases was only low to middle.  In the group of middle ripening varieties ‘Korona’ suffered under the hot weather in June 2006 and reacted with heavy wilting symptoms, first of all caused by Verticillium, and with more  leathery  and  small  fruits.  ‘Florence’  and  ‘Peco’  had  often  sunburst  (by  intensive sunbeams). ‘St. Pierre’ had a vigor plant, middle yield and less sunburst, but should be picked well ripened. The late variety ‘Yamaska’ was robust, but tasted  only middle good. The biodegradable mulch film increased in the  first year the yield of the early ripening varieties, in the second year with a hot summer this effect disappeared. Partly snails used the mulch film as refuge, damages of the film also were caused by birds. The natural decomposition  was  sufficient,  when  the  film  was  tilled  into  the  soil  after  the  second harvest.Keywords:  Strawberry,  variety  testing, soil-borne  diseases,  biodegradable  mulch  film, organic cultivation IntroductionMain problems in organic cultivation of strawberries are losses by fungal attacks (dying of the whole plants, smaller fruits because of disturbed nutrition from the roots, infections of the fruits by Botrytis cinerea). The choose of suitable varieties is very important for the success  of  organic  strawberry-cultivation.  From  1998  to  2004  trials  about  suitability  of different strawberry varieties were carried out on the organically managed experimental orchard Katzental of the LVWO Weinsberg, where the soil had a high content of silt and clay.  Often  many  losses  were  caused  by  soil-borne  diseases  like  Phytophthora  sp.  or Verticillium sp. Based on the results from Katzental further trials about variety-testing were initiated  2004  in  the  new  organic  part  of  the  experimental  station  Obstversuchsgut Heuchlingen of the LVWO Weinsberg, while the orchard Katzental changed to another department. The use of biodegradable mulch film and its influence on ripening and yield was an important aspect of that trial.                                                 1 Barbara Pfeiffer, Staatliche Lehr- und Versuchsanstalt für Wein- und Obstbau, D-74 189 Weinsberg (Germany), e-mail: barbara.pfeiffer@lvwo.bwl.de Archived at http://orgprints.org/13658/134Material and Methods The experiment had two main themes: •  comparison of two origins of potted plants (‘Honeoye’ and ‘Korona’) •  influence  of  biodegradable  mulch  film  on  healthy  and  yield  of  different  varieties (‘Honoeye’, ‘Clery’, ‘Elsanta’, ‘Darselect’, ‘Korona’, ‘Kent’, ‘Florence’, ‘Yamaska’) In  August  2004  potted  plants,  which  were  all  propagated  in  organic  nurseries,  were planted with 1,0 m x 0,3 m distance. The advance culture was self seeding of rye, water was given by drip hoses. Per variety 25 plants were planted without repetitions, each variety was proofed with and without biodegradable mulch film (Materbi-film, produced by NOVAMONT  from  maize  starch,  black  colour,  20  µ).  Altogether  the  trial  had  20  regular parcels,  additional  the  varieties  ‘St.  Pierre’  and  ‘Peco’  were  planted,  which  were propagated  conventionally.  During  the  whole  duration  of  the  experiment  the  vigor, infections  by  leaf-diseases  (four  classes:  weak  /  weak  to  middle  /  middle  /  heavy infections),  losses  by  soil-borne  diseases  and  striking  details  during  blossom  were evaluated.  The  yield  was  registered  in  the  years  2005  and  2006  and  divided  in  these classes:•  damages  like  deformations  by  low  temperatures,  infections  by  Botrytis  cinerea,leathery berries, other losses (sunburst, snails, birds, beetles) •  size of healthy fruits: < 22 mm, 22-25 mm, 25-30 mm, > 30 mm As marketable yield the weight of all fruits > 25 mm were summarized. In 2006 additionally the average fruit weight was evaluated from the classes 25-30 mm and > 30 mm. On April 25th 2005 a light frost caused damages at the blossoms, although they were covered with fleece, and as a result of that some more deformations were seen at harvest. Beginning with the first weak of June the maximum temperature was below 20 °C for 10 days, afterwards it was warm, at the end of the harvest season very hot (maximum often higher than 30 °C). Rain was seldom during harvest season of strawberries in 2005. One year later more rain fell at the beginning of harvest, so some more infections of the fruits by Botrytis  cinerea  were  assessed.  At  the  end  of  June  2006  during  ripening  of  late varieties it rained nearly every day, so the fruit quality was reduced. ResultsTable 1 summarizes evaluations of leaf spot during the whole running of the trial. The intensity of attack depended from the weather conditions in summer and autumn. Plants with  heavily  infected  plants  nevertheless  could  bear  a  sufficient  yield.  The  stands  of ‘Honeoye’,  ‘Elsanta’,  ‘Korona’  and  ‘Kent’  were  a  little  bit  uneven,  some  plants  died. Typically for ‘Darselect’ were light green leaves with suboptimal contents of Mg and Fe.  ‘Clery’, ‘St. Pierre’, ‘Yamaska’ and ‘Florence’ had a vigorous stand.  Table 1: Sensibility of the tested varieties for leaf spot (Mycosphaerella fragariae)Infections  varieties weak  Kent, St. Pierre, Peco, Yamaska weak-middle  Darselect, Florence middle  Honeoye, Elsanta heavy  Clery Archived at http://orgprints.org/13658/135In table 2 some data from the comparison of the two origins of ‘Honeoye’ and ‘Korona’ were listed, based on the plots without mulch film. Both varieties lost only < 1% by Botrytiscinerea in 2005 and nearly 2 % in 2006. Deformations (3-9 %) and feeding damages by snails, birds or beetles (10-15 %) were more important. Table 2: Comparison of two origins of ‘Honeoye’ and ‘Korona’, marketable yield (g/plant) from plots without mulch film Variety/origin  2005  2006   25-30 mm  > 30 mm  25-30 mm  > 30 mm Sum 2005+2006 t/ha * ‘Honeoye’ origin 1  84  349  310  384  32,1 ‘Honeoye’ origin 2  75  276  259  532  32,5 ‘Korona’ origin 1  75  194  187  186  18,3 ‘Korona’ origin 2  111  213  232  243  22,7 * only 28 500 plants/ha, assumption of 5 % losses of the plants In 2006 (second yield) more smaller fruit were harvested, because the plants had many inflorescences. ‘Korona’ from origin 1 had less marketable yield because of damages like sunburst and leathery berries. For organic cultivation the yields were sufficient.  An important effect of the biodegradable mulch film in the year 2005 was an increasing of  the yield of the most early and middle ripening varieties (‘Clery’ + 13 %, ‘Elsanta’ + 8 %, ’Darselect’  +  39  %),  in  2006  the  opposite  happened  (‘Clery’  -  8  %,  ‘Elsanta’  –  39  %, ‘Darselect’ – 18 %) . Ripening of 'Clery' and 'Elsanta' during harvest 2006 05010015020025030035031.05. 07.06. 14.06. 21.06. 28.06. 05.07. 12.07.total yield g/plantClery  Clery + film Elsanta Elsanta + filmFigure 1: Ripening 2006 of the early varieties ‘Clery’ and ‘Elsanta’ (total yield, g/plant) In figure 1 the influence of using biodegradable mulch film is shown for the early ripening variety ‘Clery’ in comparison to ‘Elsanta’. ‘Clery’ reacted with an earlier beginning of the picking season, ‘Honeoye’, too. At the middle and late ripening varieties this effect couldn’t be watched so clearly.Material and Methods The experiment had two main themes: •  comparison of two origins of potted plants (‘Honeoye’ and ‘Korona’) •  influence  of  biodegradable  mulch  film  on  healthy  and  yield  of  different  varieties (‘Honoeye’, ‘Clery’, ‘Elsanta’, ‘Darselect’, ‘Korona’, ‘Kent’, ‘Florence’, ‘Yamaska’) In  August  2004  potted  plants,  which  were  all  propagated  in  organic  nurseries,  were planted with 1,0 m x 0,3 m distance. The advance culture was self seeding of rye, water was given by drip hoses. Per variety 25 plants were planted without repetitions, each variety was proofed with and without biodegradable mulch film (Materbi-film, produced by NOVAMONT  from  maize  starch,  black  colour,  20  µ).  Altogether  the  trial  had  20  regular parcels,  additional  the  varieties  ‘St.  Pierre’  and  ‘Peco’  were  planted,  which  were propagated  conventionally.  During  the  whole  duration  of  the  experiment  the  vigor, infections  by  leaf-diseases  (four  classes:  weak  /  weak  to  middle  /  middle  /  heavy infections),  losses  by  soil-borne  diseases  and  striking  details  during  blossom  were evaluated.  The  yield  was  registered  in  the  years  2005  and  2006  and  divided  in  these classes:•  damages  like  deformations  by  low  temperatures,  infections  by  Botrytis  cinerea,leathery berries, other losses (sunburst, snails, birds, beetles) •  size of healthy fruits: < 22 mm, 22-25 mm, 25-30 mm, > 30 mm As marketable yield the weight of all fruits > 25 mm were summarized. In 2006 additionally the average fruit weight was evaluated from the classes 25-30 mm and > 30 mm. On April 25th 2005 a light frost caused damages at the blossoms, although they were covered with fleece, and as a result of that some more deformations were seen at harvest. Beginning with the first weak of June the maximum temperature was below 20 °C for 10 days, afterwards it was warm, at the end of the harvest season very hot (maximum often higher than 30 °C). Rain was seldom during harvest season of strawberries in 2005. One year later more rain fell at the beginning of harvest, so some more infections of the fruits by Botrytis  cinerea  were  assessed.  At  the  end  of  June  2006  during  ripening  of  late varieties it rained nearly every day, so the fruit quality was reduced. ResultsTable 1 summarizes evaluations of leaf spot during the whole running of the trial. The intensity of attack depended from the weather conditions in summer and autumn. Plants with  heavily  infected  plants  nevertheless  could  bear  a  sufficient  yield.  The  stands  of ‘Honeoye’,  ‘Elsanta’,  ‘Korona’  and  ‘Kent’  were  a  little  bit  uneven,  some  plants  died. Typically for ‘Darselect’ were light green leaves with suboptimal contents of Mg and Fe.  ‘Clery’, ‘St. Pierre’, ‘Yamaska’ and ‘Florence’ had a vigorous stand.  Table 1: Sensibility of the tested varieties for leaf spot (Mycosphaerella fragariae)Infections  varieties weak  Kent, St. Pierre, Peco, Yamaska weak-middle  Darselect, Florence middle  Honeoye, Elsanta heavy  Clery Archived at http://orgprints.org/13658/136In  figure  2  the  marketable  yield  (Sum  2005+2006)  is  described  for  different  varieties, cultivated  without  biodegradable  mulch  film.  Summarizing  both  years  ‘Clery’  and ‘Darselect’ had a lower marketable yield, but ‘Clery’ ripened earlier, so the fruit can be sold with higher prices. At the harvest ‘Darselect’ started only 2-3 days before ‘Elsanta’, during the whole harvest season the yield was lower, but the weight of the fruits was higher, so the picking efficiency was higher. St. Pierre showed in the earlier trials in Katzental healthy and vigorous plants. In this experiment the vigor was comparable, the colour of the fruits is light red, so only well coloured strawberries should be harvested.Marketable yield  of organic strawberries2005+2006, cultivated without mulch film05001.0001.5002.0002.500CleryHoneoyeElsantaDarselectKoronaKentSt. PierrePecoYamaskaFlorenceg/plant> 30 mm 2005 25-30 mm 2005 > 30 mm 2006 25-30 mm 2006Figure 2: Marketable yield (sum 2005+2006, g/plant), plots without mulch film‘Korona’ tasted well, but had problems with plant healthy in the second harvest season, because the plants started to wilt by Verticillium sp. In combination with mulch film one of the origins was less healthy, the film seemed to increase wilting. ‘Kent’ is an older middle ripening variety, with yield similar to ‘Elsanta’ and less hard fruits, but sensibility for Botrytis cinerea was a little bit higher. ‘Peco’ was planted late in August 2004 because of delivering difficulties,  so  the  marketable  yield  was  low.  Besides  the  dark  red  fruits  were  often damaged by the sun in the hot summer 2006. In 2006 the percentage of deformations was lower than the year before (‘Darselect’ 42 % in 2005!), but more botrytis-infections were found, especially at the early ripening variety ‘Clery’ (3,4 % in 2006). Worth mentioning were losses by leathery berries at the varieties ‘Elsanta’, ’Korona’  and ‘Kent’. Both  late  ripening  varieties  ‘Florence’  and  ‘Yamaska’  had  high  total  yields.  Altogether  fruits often were sorted out because of sunburst or feeding by snails, carabids or birds, partly the loss of yield was very high (between 85 and 463 g/plant, see figure 3). ‘Florence’ had high losses by damages like sunburst, stained fruits or feeding. The snails seemed to prefer  the  varieties  ‘Darselect’  and  ‘Florence’,  they  spurned  the  less  sweet  varieties ‘Honeoye’ and ‘Yamaska’. Some factors like sunburst are difficult to influence in organic cultivation, especially in times of extremely changeable weather conditions. Archived at http://orgprints.org/13658/137Why fruits were sorted out in season 2006?0100200300400500600700CleryHoneoyeElsantaDarselectKoronaKentSt. PierrePecoYamaskaFlorenceg/plantother lossesleathery berriesbotrytis < 22 mm22-25 mmdeformationsFigure 3: Fruit losses (g/plant) in summer 2006 About handling of the biodegradable mulch film (originally used in the short cultivation of cucumbers)  the  following  points  must  be  mentioned:  After  the  first  harvest  season  the mulch film was damaged at some points, because during hot weather craws tried to reach the drip hoses. If bindweeds grew under the mulch film and were drawn out by hand, the film broke. On sites where bindweeds or thistles are a problem the mulch film should not be  used.  The  film  perished  first  at  the  places,  where  an  intensive  contact  to  the  soil existed. There also was a small area, where weeding could not be done with the rotary tiller.Discussion The biodegradable mulch film had some advantages (less weeds in the row). Temperature above the black mulch film can be very high during sunny days, this was a result of a trial in  organic  cultivation  of  vegetables,  where  black,  green,  red  and  brown  biodegradable mulch films were compared (Postweiler, 2006). Using mulch film must be combined with drip hoses under the film, the moisture of soil under the film should be controlled regularly, even if natural rainfall seems to be sufficient. In both years the yield of the most tested varieties was high enough for organic cultivation conditions, but in other evaluations on organic fields lower yields per plant were found (Eis & Pfeiffer, 2007). Acknowledgements Thanks to all members of the staff of the Obstversuchsgut Heuchlingen, who helped us during the picking seasons of strawberries 2005 and 2006. References Eis,  B.;  Pfeiffer,  B.  (2007):  Anbausysteme  und  Kulturführung  im  ökologischen  Erdbeer-  und Strauchbeerenanbau  zur  Erhöhung  der  Bestandssicherheit  (incl.  Strategiien  gegen Verunkrautung). Schlußbericht Forschungsprojekt 03OE087, Laufzeit 2004-2006. Postweiler,  K.  (2006):  Einsatz  biologisch  abbaubarer  Mulchfolien.  Thüruinger  Ökolandbau-Fachtagung, Tagungsband, 23-28. Archived at http://orgprints.org/13658/

Testing of strawberry-varieties (with/without biodegradable mulch film) for organic cultivation

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