Application sheet
A026 Open field Strawberries
Background
Many countries produce strawberries locally to compete with bulk American and Spanish production. The Open Field strawberry is a seasonal fruit
that is harvested during 6 weeks. Since half of the yields are obtained in
the first 15 days of harvest, the price of strawberries is closely related to the
available supply volumes. It is economically important to create an early
harvest crop to get the best prices.
This is enabled by the choice of early ripening varieties and enhanced by
the use of fleeces. While early varieties create the capability of earlier
fruiting, the plants can still yield low quantity and quality. Protection using
fleece is becoming increasingly common, especially in Germans production
areas as a method of maximising the yield one fruiting commences
Cultivation
Strawberry cultivars can be planted in fields from the beginning of spring until late autumn. Exact
timing depends on the method of cropping, the type of plants, climate, variety and targeted
business objective.
Initial use of a mulch during planting reduces weed growth whilst helping to retain soil
temperature which encourages rooting. A black mulch such as Agryl M increases soil temperature,
regulates and improves the uniformity of retained moisture. As a result, development and recovery of plants during the first 3 months following planting are much faster for mulched soil than
bare soil.
Negative temperatures are limiting factors of yield and fruit size [2]
Strawberries are sensitive to frost with any damage being visible from durable temperatures of
-10°C to -15°C [5]. However, from -6 ° C, damage in primary flowers are observed [1]. The first year
plants have few primary flowers that it is important to protect. Our Agryl fleece help to protect
strawberry crops when they are sensitive by reducing frost damage.
Duration and installation of covering
To protect strawberry plants from frost, the fleece can be installed from November to early January, depending on
weather conditions. For extra thermal protection, nonwoven
can be doubled or covered with a 500 or 750 holes PE film.
In all cases, the crop cover is removed when about 10% of the
flowers are blooming to allow pollination. However, the fleece
should be left beside the plot, so that the plants can be
covered quickly in case of negative temperatures. It is
therefore preferable to anchor the fleece with bags (filled with
sand) that allow more flexibility to install / remove the crop
cover compared to studs of earth.
Application sheet
A026 Open field Strawberries
Advantages of crop cover
•
Thermal protection from frost: A temperature difference of about 3°C is recorded at the
rosettes level between plants protected with Agryl P17 [2] and un-covered plants. With
Agryl P30, this difference increases to about 6 ° C [2].
+6.9 °C
+0.5°C
Air temperature
2 sheets of Agryl P17
Agryl P30
In addition, the installation of two layers of Agryl P17 provide better thermal performance
than a single layer of Agryl P30 [3].
•
Improving yield and fruit size:
size Frost being a limiting factor in the size and yield fruit, the
use of crop cover can significantly increase the early yield. However it has no impact on the
total crop yield [4]. Experiment with 'Honeoye' variety shows a gain of 43% in yield (harvest
in g / plant) and 25% by average weight per fruit with Agryl P17 compared to bare soil. [6]
•
Improved earliness
earliness: Fleeces can improve the thermal conditions and therefore the conditions for plant growth. With ‘Elvira’ variety, early harvest can be improved by 13 days [6].
•
Insect protection:
protection The first year plants have few flowers, therefore it is important to protect
them against pests, in particular weevils which loosen buds. Tests conducted on "Bounty"
variety showed a decrease of 30% in flowers damage with Agryl P17 laid at the first flight
and removed when 50% of the flowers are blooming. The installation of the crop cover appears to be even more effective than treatment with Pyrethrum. [7]
Reference
http://www.planetoscope.com/fruits-legumes/1168-production-mondiale-de-fraises.html
[1]
Fuller H. P. et al, 1989. Evaluation of four row covers for winter and spring freeze protection of strawberries in Eastern
North Carolina. NAPA Congress. P240-246.
[2]
Nestby R. 1997. Influence of wintercovers on crown temperature, tissue browning and yield of ‘Korona’ strawberries. Acta
Hort. 439 Vol. 2 ISHS 1997. p887-891.
[3]
Painchaud J., 2003. Bâches, précocité et rendements avec des plants multicellules. 5P.
[4]
Poling E. B. et al, 1991. Frost/Freeze Protection of Strawberries Grown on Black Plastic Mulch. Hortscience, vol 26(1), January 1991. P15-17
[5]
Roudeillac P. et al. , 1987. La Fraise Techniques de production. CTIFL, Paris. 384P.
[6]
Seipp D., 1991. Verfrühung von Erdbeeren. ObstBau 4/91. P 216-219.
[7]
Svensson B. , 2002. Organic Growing of Strawberries, with Control of Insects and Mulching/Fertilisation. Proc. 4th Int.
Strawberry Symp. Eds. T. Hietaranta et al. Acta Hort. 567, ISHS 2002. P419-422.
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