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!

This last two weeks has seen Haygrove Farm in England hosting growers from all over the UK and, latterly, from many other countries as part of our Autumn Open Day series. It has been great to be part of these events – not least because we all learn so much from the interchange of ideas that comes about when growers get together and feel able to talk openly about their experiences testing new ideas and kit. Over the next few weeks this blog will probably report on some of the ideas presented and experiences shared at the Open Days.

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!

With stories of ‘fish kill’ due to unusually low water temperatures in Florida perhaps it was the wrong time to visit! Even Florida has a winter.

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.

Written from the Eastern Great Lakes areas of North America where tunnels are seen as a route to sustainable farming.

Seeking to extend the growing season and make more crops possible for farmers to grow and sell to local outlets University extension workers have done fantastic work on high tunnel growing systems. Local communities are now reaping a rich and diverse harvest from all that work both in terms of farm incomes, a wave of genuine enthusiasm for local fresh produce, a better understanding of where food comes from and technical know-how.Successful research projects range from high tech field scale systems for covered cherry production at MSU and Cornell, through work on berries and flowers to some wonderful “Community Supported Agriculture” or CSA projects.

CSA type projects are working in both rural areas and cities, not least those such as Detroit, now suffering from a contracting automotive industry. USDA’s Natural Resources Conservation Service (NRCS) has been inspired to offer financial assistance for some New York State farmers to establish seasonal high tunnel systems for crops (http://blogs.cornell.edu/hightunnels/).

Adam Montri of Michigan State University has been lighting up winter grower meetings with his enthusiasm for ‘hoop house’ horticulture. Adam, like many American horticultural extension specialists also runs his own farm in partnership with his wife, growing a wide range of fruit, vegetables and flowers.  To find out more visit Adam’s blog http://hoophouse.msu.edu/blog/index.php

Adam has perfected a technique for growing leaf salads right through the Michigan winter without supplemental heating. Inside a “four season” tunnel and under a layer of row cover (fleece) the crops continue to grow for a monthly cutting cycle despite icy conditions outside. Recent measurements for a similar system managed by Cornell scientists showed that a soil temperature of 33°F (1°C) was maintained under the fleece despite outdoor temperatures down to -9°F (-23°C).

Whereas in Britain growers are more familiar with using terms like “Three Season” to describe the useful life of the polythene films used to cover tunnels and hoop houses the Americans use the same terms to differentiate between types of tunnels. “Four Season” tunnels are those that remain clad through the whole year – Spring, Summer, Autumn (Fall) and Winter. These tunnels are strengthened to withstand snow. With 20” (50cm) of wet snow falling in 24 hrs at several sites during February this extra cost is vital. Field scale tunnels are normally built as “Three Season” structures being de-skinned before heavy snow is expected. This ‘time of’ is actually quite useful for many crops – providing the required rest period for berry and cherry crops, some additional spider mite suppression and cleansing of the soil where unwanted salts have built up during the growing season.

Get growing!