Scottish growers had weather that was as warm as mid Summer last week but many centimetres of snow this week! Away from the most extreme winds of snow this weather is annoying for tunnel growers but not dangerous…. but what to do about doors?

Unless the location is very sheltered, Haygrove recommend Streamline doors for temporary and fixed tunnels where extreme earliness is required. Withstanding strong winds these doors and adding to the structural wind resistance of tunnels ends, Streamline doors provide 100% sealing.

Streamline door fitted to Solo tunnels

Most berry growers growing under 4-Series type tunnels on temporary sites opt for simple, low cost doors of the type shown in the image below. Makes sense…. cheap, quick to install etc.

Simple door, in open position (tied back to hoop)

….. But the climate is never right and every time the weather changes the grower must decide whether to spend money on labour, opening or closing OR lose yield or quality by compromising on the growing environment.

By far the best doors for field scale tunnels are ‘roller doors’. Unless the tunnels ends are staggered instead of straight of swept, roller doors can be set up to open several tunnels at once. Haygrove Farm now has many blocks kitted out with roller doors and for semi-permanent substrate fields the doors are now motorised. The new table tops have both doors and roller vents linked to climate sensors. Now we can concentrate on the plants and not the labour cost! 

Roller vents controlled by climate sensors

Having said that I note the following ‘facts’ from Wikipedia at http://en.wikipedia.org/wiki/List_of_weather_records

Highest amount of rain in one year = 26,470mm (Cherrapunji, India)

Average annual total rainfall = 11,872  (Mawsynram, India)

Most rain in 12 hours = 1,144 (Foc-Foc, Reunion)

Most rain in 1 hour = 305mm (Holt, Missouri)

However much people complain about British weather, we appear to be pleasantly dry by world international standards and now un-pleasantly dry for strawberry growers!

At our British Haygrove Open Days we discussed water conservation and erosion control. We based our calculations on an average rainfall of 792mm (for Ross-on-Wye, Herefordshire) but also presented calculations based on provisional data for 2011. I was shocked when speaking to a leading grower and nurseryman from the East of England, to find that he had recorded only 100mm of summer rain. I have subsequently discovered that the April-August total for Ross was actually a similarly low figure (97mm).

Figures from:

http://www.metoffice.gov.uk/climate/uk/stationdata/rossonwyedata.txt

Average = 1971 – 2000

We were demonstrating a mobile steel gutter forming system and calculating how much the water collected from guttered fields, during the covered season, could contribute to the total need of the crop. Allowing for the fact that, due to evaporation, only about half of the rain landing on a tunnel would be collected by the gutters we calculated that in a relatively dry year like 2011 we could collect 25 -30% of crop need. In a normal year the number would between 45 and 75% of need.

Haygrove Guttering System

In the UK ‘mains’ water can cost commercial farmers £1.30 per m³. Water from the gutters could therefore save £1,300 and £2,000/ha. The collected water is also largely free of salts – great for salt sensitive crops and for diluting saline water supplies.

Statistics from Mark Else at East Malling Research (http://www.emr.ac.uk/) show that a commercial crop of soil grown strawberries requires around 70 m³ irrigation water per tonne of harvested fruit. With some sophisticated sensor equipment it is possible to make substantial reductions in irrigation requirement. East Malling has suggested a target of 10m³ per tonne although the industry has yet to see whether this will sustain the consistently high yields it requires to remain competitive.

Even though table top and glasshouse systems are completely dependent on a ready supply of water the high yields achieved tend to bring the water use per tonne significantly below the 70m³ average.

For me it is clear that growers will be investing more in soil moisture sensors and decision support systems but I also foresee a big increase in gutter installations both to collect water from the roof and to collect drain-water from soil-less growing systems. It is likely that many growers will also be forced to re-cycle/re-circulate that water.

UK yield and value rising despite a declining area of production

A closer look at the data shows clearly that the increased value came from increased yield per hectare. The exciting thing about this is that right up to 2009 the average yield continued to increase. British producers deserve much praise for achieving this. A never ending stream of innovations or early adoption of new ideas from other countries has seen dramatic changes in plant quality, varietal development and planting systems (and covering structures!) that has sustained the momentum of increasing yields.

Traditional Type Planting - 'on the flat' and outdoors.

Where we are now. Excellent raised bed production under Haygrove tunnels with mechanised ventilation.

New raspberry pots with on line drippers installed

At the time of writing growers in England are recovering from the season and planning for 2012. We normally get enough rain for crops such as apples and cherries but 2011 was a very dry year.

Tree fruit growers are also planting at much higher densities (trees per acre or hectare) now – I do not hear of many new commercial apple plantings with in row tree spacings wider than 1.25m and most are 1m or less. These trees don’t have to grow much but they have to crop quickly and consistently from year to year in order to get payback within an acceptable number of years.

A dry year and a focus on early pay-back means that fertigation is much discussed right now.

 For tunnel grown crops, irrigation is an ESSENTIAL.

 For growers who have not previously needed to use irrigation this will be an important change and requires some learning.

For growers who have been using irrigation/fertigation on outdoor crops there may also be some important changes to make. One American pundit wrote that ‘Tunnels Change Everything’ and they do….mostly for the good…..but when it comes to fertiliser, tunnel grown plants are able to make more efficient use of key nutrients. There is less leaching of nitrogen and soil temperatures are higher. Reduced wind and UV light also promote the production of larger leaves.

Tomato growers tend to space the plants out a bit more, the same may rule apply to strawberries. However for tree crops, such as cherries, there may be other changes that can be made: More dwarfing root-stocks or perhaps even planting the trees even closer together!

Spring of 2nd year for cherries planted directly into tunnels

Why closer together? Planting close usually facilitates a more rapid year on year ‘yield build up’. Planting under tunnels provides a level of crop insurance so that the extra investment in trees is a safe one. Modern tree fruit growers know that closer planting actually makes vigour control and regular cropping easier. The trick is to manage the first months and years after planting so that the trees concentrate on fruit growing and not on timber production. Making sure that tunnel grown trees do that requires some thought and the management of irrigation should be the subject of a lot of that thought!

However to start this season of posts the blog returns to the subject of earliness but approached from a different angle. One of Haygrove’s farm managers, Adrian Pop, reported that his weather station data showed that, during the month of September, tunnels fitted with gutters had accumulated 15% more growing degrees than the same tunnels not yet fitted with gutters.

September is usually the last warm month and British growers need that warmth to ensure adequate yields from everbearer strawberries, late planted table tops and primocane raspberries. Many growers will also have a 2^nd crop of a short day strawberry variety growing on table tops for which good Autumn temperatures are essential both to finish the crop and to build good plants and flower numbers ready for the following Spring.

So what does 15% more growing degrees give us?

A typical everbearer might yield 4 tons per acre in England through the month of September and that is directly dependent on growing degrees. Most of the flowers required to produce that fruit will have already emerged and been pollinated before or during the first days of the month.

15% x 4 tonnes = 600kg = worth at least £1,000 net of picking and post harvest costs.

Another way to look at it would be to say that under tunnels with gutters, September has 34 instead of 30 days!

Cherry flower, Haygrove Farm organics 2010

Even as early as December English strawberry growers will be planting cold stored plants that have received enough chilling and glasshouse salad crops will be taking delivery of new plants for early, heated crops. Both these will be have consider pollination very carefully and will be using bumble bees.

Some important points to remember if you are planning to seal up your tunnel or glasshouse for maximum earliness:

• If the structure is sealed to retain heat (or to exclude insects) pollinating insects will need to be placed on the inside or flowers pollinated by hand
• Bumble bees are best for pollinating early crops. They are not aggressive and fly at relatively low temperatures.
• Don’t forget that, if the sun comes out, temperatures in a sealed structure will rocket upwards. That will cause bees to retreat to their hive, on fanning duty, to protect their brood and will also mean that your plants are use more energy respiring than they make photosynthesising. For most crops its not a good idea to let the air temperature rise above 25 degrees C.
• For small structures its usually best just to leave the door open and let local bees and other nectar feeding insects do the pollinating. For tomatoes many growers appear to find that their own business and some air movement provides pollination.

Open flower at a farm near Hereford, England

Last week Haygrove organised a “Specialist Cherry Day” in the Canterbury area of Kent.

The day started out 2 miles from the location by chosen by advisers to King Henry VIII as the best place in England to grow cherries!

The morning was spent at Little Sharsted Farm and the afternoon at Hoaden Court Farm. With more than 100 growers and market specialists attending, Haygrove were very grateful to the owners and staff of the two farms at what is a busy time of year for all fruit growers. We were blessed with excellent sunny weather with the cherries in glorious full bloom.

These farms are located in one of the driest regions of England.

Although overseas followers of this blog will be interested to note that there any ‘dry’ spots in England there has been some debate about the need for rain protection in these areas. However losses reported by Hoaden Court and the value of an 8 ton/acre crop clearly justifies the investment – not least when important customers are relying on the grower to supply.

Prior to the lunch break a short talk was given describing some developments and techniques in Chile and Michigan. The latter focussing on the work of Prof. Greg Lang of Michigan State University on the growing of sweet cherries under ‘high tunnels’. A link to a poster presentation summarising some of Prof. Lang’s recent research work follows.

http://www.hrt.msu.edu/faculty/langg/Sweet_Cherry_Research.html

Select the HIGH TUNNEL CHERRY PROJECT tag to view the poster in MS Powerpoint.

Young cherries, first covered in 2009

A photograph was promised.

Haygrove Solo Tunnels protecting an early Elsanta strawberry crop (Ledbury, England)

These tunnels have been fitted with polythene that is sufficiently wide to provide a continuous seal along the sides of the tunnel (film and soil in continuous contact).

Solo tunnels: Good seal between polythene film and soil at sides of the tunnel.

The grower has also chosen to fit Haygrove Streamline doors. These doors are also in use on a nearby green asparagus for for the same reason: Excellent sealing of warm air inside the tunnels and resistance to wind.

Growers using these doors have less to worry about during windy weather. In fact the doors allow the crop to remain oblivious to whatever horrible English (or Scandinavian for that matter) weather is happening outside!

Haygrove Streamline Doors fitted to tunnels on an asparagus farm

More recently temperatures jumped upwards, taking apple growers by surprise as buds moved from very early bud break to the mouse ear stage within a few days. As is typical of the British climate, the warm air brought rain too leaving many growers ruing missed opportunities to protect orchards from scab, before the inevitable showers arrived.

With the temperatures rising, early strawberry tunnels also came into flower. For the earliest of these, first flowers appeared in the week leading up to 25th March. Even though the cold returned last week, pasture has greened up and there is evidence of Spring everywhere in the South.

It is surprising that there is still discussion about the most effective way to bring on early strawberry crops under tunnels when it seems so obvious in the field!

GOOD SEALING + FLEECE + FLOATING MULCH

In the other countries fleece = ‘row cover’ and floating mulch = “perforated film” or “perforated poly”

When temperatures dropped last week well sealed SOLO tunnels remained warm and when the strong winds hit us at the end of the week growers were able to keep them closed, especially when fitted with STREAMLINE doors.

To avoid damage from Feb-March winds the safest option is to delay tunnel skinning and rely on ‘fleece and floating’ alone or to choose stronger tunnel designs such as the SOLO (with 2mm wall steel).  In Britain the best money still comes from early crops so, for strawberries the industry is gradually moving towards much stronger tunnels.

It has a Winter…..but a very productive one. For a Northern European strawberry grower, Florida can be confusing. Fields are established in September, often using plants lifted up in Canada, and harvest starts in ? The varieties plants are primarily those that require short days to initiate fllowers. Tha main June bearing strawberry varieties grown in Germany, Holland and Belgium are also ‘short day’ varieties (Elsanta, Sonata, Cambridge Favourite, Korona etc.) but in those countries there is only a relatively short period during which ‘short days’ coincide with temperatures that are sufficient to support growth and development. For the rest of the time the plants must be dormant in order to withstand the Northern Winter. In Florida the initiated flowers don’t wait for the end of Winter. They are expressed immediately and keep coming: Providing a crop from ? right through into April at which point growing conditions in California give that state the edge and Florida drops out.

As the fish kill reports suggest – the climate is not always perfect. Florida strawberry growers cope with many challenges. Rain comes frequently causing several important problems:

RAIN =

• Misshapen fruit
• Collectotrichum crown and berry rots
• Xanthomonas leaf spot.

Growers are increasingly working with field scale tunnels in an attempt to eliminate these problems and to increase early production.

At the Gulf Coast Research Station Vance Whitaker is responsible for breeding better berries for Florida. Work at this station, directed by Craig Chandler, has produced many famous strawberry varieties. Conditions in the Florida winter are so favourable to infection that Vance must be ruthless in discarding any materials that shows susceptibility to crown rots. This research station is right at the front line when it comes to matching horticultural science with the needs of a changing world. Up in Michigan, Ontario and New York there is lots of excitement about small scale, local and very sustainable production. Down in Florida they are scaling up! Working on better systems for the production of various key horticultural crops. Helping growers in Florida and around the Caribbean to meet the rising demand for fresh, clean, fruit and vegetables. In the Caribbean this work is especially important because it is raising farm incomes and the living standards of whole communities. The impact of this is global.