CROP CRACK - 15.09.07
By WENDY FEARON
Clarendon Agricare - Grassland Reseeds

Most of the cereal harvest has now been completed with reported yields being variable but at best average with reports of some poor quality samples. Attention is now turning to autumn cultivations and drilling of winter crops. 

Some main crop potatoes have now been desiccated and successful harvesting and storage is now the main aim. Harvesters should be carefully set to minimize damage to the crop as damaged tubers allow easier infection by storage diseases. 

Grass reseeding has finally begun and swards should be inspected for weeds and pest damage and treated where necessary while ground conditions still allow.

WINTER CEREALS

Thanks to the drier conditions last weekend most of the cereal crop has now been harvested and some autumn drilling has begun. For farmers aiming to grow“second wheat” Jockey and Latitude are available as seed treatments to help control take-all and growers requiring these treatments should order early.

With ever-increasing attention being given to biofuels and with contracts available locally, the acreage of oilseed-rape looks set to increase even further this autumn.

In order to achieve its full yield potential, successful establishment is critical. Most crops should be sown now – the cut-off for drilling is latest by mid September.

Adjusting the seed rate to achieve the desired plant stand is the primary factor in determining the entire crop’s agronomy for successful canopy management. Depending on variety & sowing date, sowing rate is somewhere between 4-8kg/ha to achieve an optimum of 50-70 plants/m²; this may appear sparse but these crops will outperform a 100+ plants/m² crop. Seed-to-soil contact, moisture availability, consolidation and compaction are also key factors affecting good establishment.

Once established, oilseed rape seedlings are extremely vulnerable to early competition for light and moisture from both broad-leaved and grass weeds. Just 20 volunteer barley plants per m2 can reduce oilseed rape yields by 0.15t/ha; 150 volunteers could reduce yield by over 1.0 t/ha. Uncontrolled weeds will also adversely affect the quality of seed harvested. Cleavers, chickweed & mayweed are the most damaging broad-leaved weeds (BLW).

There are two products commonly used, BUTISAN and KERB FLO. Both are dependant on root uptake and therefore require soil moisture to be active - dry soils will result in poor results. Both work most effectively on fine, firm seedbeds; not as effective with cloddy seedbeds. Crop selectivity is by depth protection – it is important to ensure seed is well covered by soil to a depth of 15mm min. Do not use either if heavy rain is forecast shortly after application or crop damage will occur. Neither will be effective where soil organic matter levels are above 10%.

Following a major yellow rust outbreak, it is typical for some varieties to break down and for new races to appear.Robigus will remain the key variety susceptible to rust, so a broad spectrum seed treatment which provides early protection plus a T0 in the early spring will be the key ways to target this variety.

Slugs have been particularly active over the summer months, their development favoured by the mild damp conditions.  These will pose a serious threat to emerging crops, especially those drilled in rough open seedbeds and particularly where low seed rates have been used.

Growers should be on the look out for these and use baited traps if necessary to assess their numbers and control them before they damage the crop.

Aphids are flying and looking to move off stubble and volunteers onto emerging cereal crops. Waiting to tank-mix the aphicide with a post-emergence herbicide may be too late to prevent a significant amount of BYDV transmission into plants.

POTATOES

Growers should continue to maintain fungicide protection of the haulm until the crop is harvested or the haulm is 100% desiccated. Timely desiccation is an essential part of good seed and ware production. Diquat is the most widely used farmer applied chemical desiccant .The rate of haulm desiccation is slow and therefore fungicide protection should continue after application.Electis, Shirlan,Invader and Option can be mixed with Reglone.Even after two split applications of Reglone certain varieties of potatoes are difficult to burn off completely and be certain no regrowth will appear.

Spotlight Plus is a new desiccant recommended for use after a 7 day interval as a follow up T2 treatment to the T1 application of Reglone and gives complete kill of any stems remaining and stolons below the ground but it is poor on leaves. Crops still in the ground are still vulnerable to attack from aphids and slugs.

As harvesting begins attention should be turning to storage. Good storage depends on minimising damage and contamination at harvest, clean dry stores and where necessary chemical treatment. 

FUNGAZIL applied as potatoes go into store will give good control of silver scurf, gangrene, skinspot, and fusarium dry rot during the storage period. FUNGAZIL can be used on ware or seed and has no “harvest interval”.

GRASSLAND RESEEDS

Emerging grass re-seeds should be inspected regularly for presence of frit-fly larvae. These will be a problem late throughout September. The larvae bore out the centre shoot causing loss of tillers or complete kill of the shoot.

If the damage is found the grass should be sprayed immediately with DURSBAN WDG.As re-seeds emerge, so to will the weeds and these are best treated early.

If weather conditions are mild it is safe to use mecoprop-p for chickweed control in grass without clover. It will also check seedling docks.Starane may also be used and is very effective on mouse-eared chickweed. These products should not be used if weather conditions deteriorate as activity is reduced. Where clover is present grass should not be treated before the one-trifoliate leaf stage.Alistell is very effective on chickweed.

GRASSLAND WEED CONTROL

Ragwort is a poisonous weed not normally eaten by stock but after treatment with hormone weedkillers such as 2,4-D or MCPA it becomes more palatable.  For this reason the best time to spray ragwort is in the autumn as this gives the weed plenty of time to die and allows a check for the efficacy of the treatment before allocating fields for silage or hay in the spring. It also minimises the necessity for livestock control.

HORTICULTURE

The relatively cool summer has delayed the 3rd generation of cabbage root fly to now, and therefore mesh covers should remain on crops unless slug pellets are required.

PROPIONIC ACID

Although we have had reasonable weather conditions at harvest, a fair amount of propionic acid will still be required. Clarendon Agricare is distributing PropiMAX (propionic acid) the new name in crop preservation. PropiMAX when applied to moist grain prevents moulds and bacterial activity. PropiMAX (propionic acid) is an active liquid preservative based on feed grade propionic acid and prevents deterioration, loss of dry matter, nutrition loss and removes the associated health hazard to grain handlers, livestock and the end user.

The addition of PropiMAX adds to the energy value of the grain. One tonne of PropiMAX on 100 tonnes of grain gives an additional energy value equivalent to 1.5 tonnes of barley. Therefore as well as preserving the grain it adds significantly to its energy value. The use of PropiMAX gives the grower greater flexibility at harvest, especially if the grain has a higher than desirable moisture content. If the weather is inclement at harvest PropiMAX offers a sense of security to the grower through its flexible application rates. PropiMAX also allows harvesting to start earlier in the morning and continue later into the evening even when dew is present.