Horticulture Notes April 2011

Firstly, thanks to Graeme Cross, Top Fruit Development Adviser, for his contribution to these notes. Graeme has now handed the pen over to me.  Introducing myself, I’m David Davidson, Ornamental Horticulture Development Adviser with responsibility for cut flowers, assisting the development of cut flower businesses. It’s been rewarding to witness growth in cut flower farm-gate sales in recent years.

CAFRE organised an on-farm workshop recently with cut flower growers at Plunketts Nurseries in Newtownards. At this event Billy and David Plunkett explained the benefits of growing and marketing locally produced cut flower tulips and daffodils. They explained that sales to local markets have been good this spring and that more local flowers could be sold.  This would allow more local consumers to make the choice to purchase in-season, locally produced, freshly harvest flowers to brighten their day. The next CAFRE workshop for anyone interested in learning more about growing and marketing cut flowers will be in early May so contact me if you are interested in knowing more.

Most local soils are acidic, neutralising them with lime will help make nutrients more available, especially for some vegetables. You might see leeks growing better in one part of a field than another, and a soil test could reveal that the area of poor growth is more acidic. You may have spread expensive phosphate fertiliser, but the acidic soil stopped the leeks from benefiting over the whole field.

Many vegetables are grown on conacre land and growers face a challenging question each spring when the soil test results come in. To lime or not to lime? Then, what sort of lime will suit best? Lime only takes effect once it has dissolved, and calcium carbonate is not very soluble. It is frustrating for a grower on rented land to bear the cost of liming when the lime may not have much effect for the first couple of months.  The benefit lasts for years, so it’s another person who benefits.

Some liming materials take effect more quickly than others, depending on their hardness and fineness. All limestone contains calcium carbonate, and some also contain magnesium carbonate. Those with magnesium carbonate tend to be harder and dissolve more slowly. Granulated limes and waste sugar beet lime all contain very finely ground calcium carbonate, so act fast, but cost considerably more than regular ground limestone. A relatively inexpensive alternative is ‘whiting’, which is regular lime ground extra fine and sold in 25KG bags or in bulk.

CAFRE is planning a vegetable on-farm demonstration this year to compare the neutralising action of different types of lime, which will be managed by the Edible Horticulture Crops Development Adviser Dr Anne Stone.

Apple bud growth is moving quickly this month, so the emphasis should continue to be on intervals no longer than 10 days between your scab control sprays.  With changeable weather, it’s sensible to include a systemic (moving through the plant) or translaminar (entering the leaf) fungicide.  These include dodine (‘Radspor’), pyrimethanil (‘Scala’) and triazole fungicides, for example, fenbuconazole (‘Indar’).  It is important that your spray programme incorporates ingredients with different modes of action throughout the season, and you combine two different types of fungicide in each spray.  Disease resistance risk rises significantly with prolonged reliance on any single chemical.

Last year’s fine spring weather encouraged a rapid development in populations of green apple aphid on expanding Bramley leaves.  These can distort leaves if present in large numbers.  However, please remember that green apple aphid is prone to a cold weather check and feeds on Bramley for only a few weeks before moving off to feed on plants in the surroundings.  If you need to apply a pesticide now, consider using an aphid specific chemical that is less destructive to beneficial organisms and the environment.  The use of broad spectrum chemicals is best deferred until later in the season.

Billy Plunkett teaching other growers about cut flower tulip production at a CAFRE workshop

John Herron explaining a point. John limes regularly to keep pH up to 7.0, and wins awards for his good crops