CROP CRACK - 21.07.07
By WENDY FEARON
Clarendon Agricare - Active Blight

There has been little let up in the challenging weather conditions this year.  Ground conditions are still far from ideal and the consistent rain and damp has resulted in severe disease pressure on all crops.  Lower than average temperatures have also put crops under pressure and growth in general has been quite slow.  Winter barley is however ripening quickly and hopefully better weather will arrive to allow the harvest to begin.

Blight pressure remains dangerously high and growers are advised to keep their spraying intervals as short as permissible.

Potatoes

Blight is now active in all parts of the province. It is therefore essential to inspect crops frequently for signs of the disease and to keep spray intervals as short as possible, appropriate of high to extreme risk conditions.

The period of fast crop growth is now almost over in most crops and it is advisable to change from systemic to translaminar products such as Curzate M or Invader or protectants such as Shirlan, Ranman, Electis or Dithane DF NT.The addition of C50 or Option to protectant products will also give curative control. The recent weather conditions have meant almost all growers using products to maximize curative activity.

Curzate M and Invader have a “kick-back” activity, which controls infection at an early stage within the plant. In more severe infections the worst patches should be desiccated with Reglone. If infection exceeds 5% (i.e. over 50 leaf spots per plant) burn of as soon as possible and wait at least three weeks after haulm death before lifting.

Inspect crops regularly for the presence of slugs and apply Draza if necessary.

Seed crops should be inspected for the presence of aphids and treat with Dovetail or Biscaya if necessary.

Spring Barley

Spring barley crops have grown rapidly with the majority now between the beginning of flowering (GS 60) and early milk development (GS 71).

Mildew levels are relatively low in most crops but Rhyncosporium is the main problem. Where crops received two fungicide treatments disease levels are low whilst crops which only received one spray are struggling now as disease pressure continues.

Winter Cereals

Early crops of winter barley are ripening quickly and some have already been cut for crimping although the conventional harvest is almost ready to begin, weather permitting.

Growth stages in winter wheat range from early milk (GS 71) to soft dough (GS 85).  The wet weather has put all wheat crops under great pressure from Septoria and late ear diseases such as Fusarium.

Pre-Harvest Weed Control

Early sown Winter Wheat and Spring Barley crops should be examined to decide whether or not they require pre-harvest treatment for the control of annual and perennial weeds, especially scutch rough stalked meadow grass, thistles etc.

Roundup Gold is the most effective and consistent product for this treatment.  It is a complete product that does not require additional wetter to be effective, even at low rates.

Roundup Gold should be applied when the grain moisture is below 30% which coincides with the hard dough development stage (GS 87).  The safe stage is 1-3 weeks prior to harvest leaving at least 7 days between spraying and harvesting.

Pre-harvest Round-up not only controls weeds but also helps to accelerate senescence of the crop making the harvest earlier, combining easier, and reducing drying costs.

Grain Store Hygiene

As harvest is approaching it is time to clean out and treat stores to avoid any losses from pests during storage over winter.  The main pests are weevils, beetles and mites, which are to be found in all grain stores.  They all multiply quickly and can cause enormous damage to grain a very short time.

When the grain store is empty before harvest, clean out the old grain, dust and any other debris, which harbor insects.  Use of an industrial vacuum cleaner makes the cleaning easier and much more effective.  After cleaning, spray all surfaces of buildings, silos and equipment with Actellic 50 EC taking care to treat all crevices and joints. This product replaces Actellic D which was only half the strength.

Grassland Reseeding

Now is the correct time to assess swards prior to autumn reseeding. To achieve effective sward destruction it is best to allow at least 2-3 weeks regrowth of the sward and spray with Round-up when there is good leaf area to absorb chemical.  Then graze or cut the sward 7 days after treatment.  This removes the foliage and allows for easier ploughing and trash burial.

Addition of Prospect to the Round up will improve the control of any docks in the sward.

Grassland

Although many first cuts were taken early this year, due to the weather since, docks in many regrowths are only now getting to the correct stage for spraying, i.e. the rosette stage.  Where possible these should be treated soon.  Doxstar and Forefront will give good control of docks but will not check the growth of struggling second cut regrowths.  Use high water volumes to ensure good coverage i.e. 300-400lt/ha (30-40 gal/acre).

There is still time to spray soft rush provided they are at the correct stage i.e. soft green and about 12 inches high.  Use Agritox 50.  If the rushes are very established with a lot of dead leaf material present then the best option would be to top them now and spray them when the soft green regrowth appears, probably next spring.

Gorse should be sprayed now.  Use Grazon 90 and ensure good plant coverage using a knapsack or handlance on a tractor mounted sprayer.

Bracken should be sprayed late July or August when it is in full frond. (When leaves are expanded)  Use Asulox and again ensure good coverage via a knapsack and where a conventional tractor sprayer is being used to treat large areas, use high water volumes at least 400l/ha. (40gal/acre).