At last, summer has arrived, UK expects ambient temperatures of plus 24 deg C, this means that tunnel temps could well climb over 28 deg C at the peak of the day. For strawberry growers, this is both good and bad news at the same time. The news is that BBQ weather is coming, the UK is on a tentative full unlock setting and many people up and down the country are enjoying what freedoms have been given back. All the more reason to celebrate with some UK grown strawberries and cream.
The downside is high heat brings with it challenges for UK growers. Strawberries are temperate crops and can enter thermal dormancy after growing temperatures exceed 28C. Strawberry crops at thermal dormancy continue to grow vegetatively but lose the ability to flower, even if there are flower buds in the crown.
This means that growers should look to vent tunnels in order to keep strawberry cooler than 28 deg C through the peak of the day. Fertigation may need to be increased in frequency so that watering can keep the roots cool. Doing this however will increase the runoff from 12% closer to 22% and should the ambient heat disappear care should be taken to reverse the system, not to overwater. This can be best achieved by keeping a steady record of the water runoff, sampling for its content, measuring the bag E.C. and crop walking.
Controlling the crop through these tricky periods can be made easier by utilising foliar feeds. Varieties such as Sonata become soft under high summer heat days, this softness can be mitigated by using YaraVita STOPIT to help firm up fruit structural cells while combining with YaraVita ACTISIL to further strengthen fruit skin density. The two applications help varieties with medium berry strength to gain better storage and shelf life.
The rapid changing temperatures from high heat during the day to cooler weather at night can present some significant fluctuations. Strawberry crops under fruiting are at a time when the crops load is significant and are very susceptible to stress. YaraVita BIOTRAC has been specifically formulated to support cell multiplication, ideal for strawberry during the green berry stage. YaraVita BIOTRAC has the ability to further mitigate both heat and cool stress, owing to its two key enzymes taken from Ascophyllum nodosum. YaraVita BIOTRAC would be an ideal foliar product to use on all soft fruit as they navigate this tricky hot/cold period, buffering the stress caused by temperature fluctuations.
With high heat and humidity after such a wet period in May, the risk of Mildew and even Botrytis will be very high. YaraVita SENIPHOS is an old favourite for changing leaf zone microclimates to less favourable conditions for these fungi to make a big impact on the crop. Again combined with a YaraVita ACTISIL application to further suppress the opportunity for Zoo spores to spread. These products should not be used in isolation but as a part of an existing fungicide program.
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