Vegetable News July 2006

Carrot fly is predicted to emerge around 26 July with egg laying beginning about a week later. Crops should be protected from early August until the middle of September.

Cabbage root fly has emerged and egg lying will be taking place. In dry conditions eggs laid in the ground may not hatch. In such circumstances it has been known for the fly to lay eggs in the plant itself and the larva then feed on the stem.

50 percent egg lay is predicted to have occurred by the beginning of next week.

Brassica growers will be pleased to know that thiacloprid (Biscaya) has received off label approval for use in Brussels sprouts, broccoli, cauliflower and cabbage for control of mealy aphid.

Thiacloprid is a stomach poison with good residual systemic action. It is the same chemical family(known as neo-nicotinoid insecticides) as imidacloprid (Gaucho). To prevent resistance developing no more than two neo-nicotinoid sprays should be givenper crop. Where Gaucho has been given as a seed treatment only one application of Biscaya should be used.

Where Gaucho has not been used two sprays of Biscaya can be applied but not consecutively. Use other insecticides with a different mode of action eg Plenum, Toppel in the spray programme. Sprout growers can also use Aztec.

Biscaya should be applied at 0.4 litres/ha. It can be tank mixed with any one of the following - Amistar, Bravo, Folio Gold, Fubol Gold, Folicur. Plover, Signum, Hallmark.

Biscaya has a seven day harvest interval.

For small to medium sized businesses a grant is available from Invest Northern Ireland for using proven energy saving technologies to reduce costs and remain competitive.

The scheme offers grants of 25 percent of the project cost, from £1,000 up to £5,000, for companies installing technologies from Energy Technology List: These include

Full details of The Energy Technology List can be found on website

Further details can be obtained from Invest Northern Ireland 028 9069 8868

Website www.investni.com/index.htm

Provided there is leaf wetness alternaria development can be rapid in warm weather. Infection can occur in 8-12 hrs and spores germinate readily in water droplets and dew.

A spray programme to control alternaria should begin in crops with well-developed canopies.

A suggested programme would be difenoconazole with azoxystrobin (AmistarTop) followed by tebuconazole (various formulations including Folicur). Spray at 2-3 weekly intervals depending on disease pressure.

For early applications target spray at the foliage - ideally using air-induction nozzles and applying at a water volume of 100 l/ha to maximise leaf coverage. As the season progresses, switching to 65º-80º vertical flat fan nozzles and increasing water volume will help spray penetration.

Cutworms are the caterpillars of certain Noctuid moths. They initially feed on the aerial parts of the plant but as they get older they move underground. They feed at night eating the stems of young plants at ground level.

If there is substantial rainfall (defined as 10mm or more of rain falling in showers of moderate intensity over a 24-hour period) whilst these caterpillars are feeding above ground then this causes high mortality. Normally this is the case in early July in N Ireland so there is generally no problem. However this year there may be damage so it would be advisable to check susceptible crops to see if there is any wilting/collapse. Check the soil about 10-25 mm below the surface and if you find a large caterpillar which curls into a "C" when disturbed that will be a cutworm.

The most vulnerable crops are lettuce, leek and red beet. Moderately susceptible crops include brassicas, carrot, celery, and parsnip.

The following SOLAs have been issued since the last Vegetable news

Joan Hamilton

Edible Crops Development Adviser

Greenmount Campus, College of Agriculture, Food and Rural Enterprise

Telephone (office) 028 9442 6683

Mobile number 077 7575 7251