CROP CRACK -19.05.07
By WENDY FEARON
Clarendon Agricare - Cereal Check

The mixture of showers and warm periods over the past two weeks has accelerated growth. Most spring barley crops are now looking well. Current weather conditions also suit the spread of Rhyncosporium and Septoria in cereals so it is important that fungicides are applied at the correct timings to maintain good cover.

Winter Barley

Most winter barley crops now have the head fully emerged (G.S.59) and are beyond the stage for applying growth regulator, unfortunately some crops have been tossed with recent heavy showers and wind. The recent weather conditions have favoured rhynchosporium and it is essential to make the correct choice when deciding which fungicide treatment to apply.T2 fungicide treatments should be applied as soon as possible.

The use of triazoles is still important in the program giving curative and protectant activity on a wide range of diseases. Punch C, Midas or Opus Team may be applied at this time and talius added for mildew control. Crops that have a good yield potential and have received a robust T1 should receive Mantra or Mobius with chlorothalonil, both products contain a triazole and strob in a mix.

Winter Wheat

Most winter wheat crops have now undergone stem elongation and are now between the flag just visible to flag leaf sheath extending growth stages (GS 37-41) with the most advanced at booting (GS 45-47). Crops should receive their T2 fungicide treatment as soon as possible. In clean crops with a high yield potential use Prosaro, Twist and chlorothalonil or Mantra and chlorothalonil.Alteratively use Opus Team. Talius should be added to varieties with a high mildew rating. Any remaining cleaver control needs to be carried out immediately using Eagle or Starane XL, (check labels for latest timings). Crops which are at risk of lodging should receive Cerone before the leaf sheath splits and the head begins to emerge, (GS 45).

Winter Oats

Most crops are now between second and third node (GS 32-33). Any crops which have not yet received chlormequat should be treated as soon as possible. Mobius or Mantra mixed with Talius should be applied if the crop has not yet received a fungicide. This offers excellent control of both mildew and rust.

Spring Barley

Although we are now into late May, leather jackets appear to be very active in the ground and it is important to continue monitoring crops at risk.
As crops now rush through the growth stages they will not have the ability to produce as many tillers and Adjust applied early (3 leaf to early tillering) will increase the number of tillers produced, and therefore boost yield.
As most crops were drilled in the same two week period there is little variation in crop growth stages with many at mid tillering.Aphids are present on all spring barley crops and I can’t stress enough the need for an insecticide to be applied. Crops should be checked regularly for them as they transmit barley yellow dwarf virus (BYDV).

Weed control should be carried out at the earliest opportunity, once all the weeds have emerged but are still small, and before they begin to compete with the crop for nutrients and light. If applied before first node (GS 31) hormone weed killers such as Foundation, Mircam or Duplosan may be used. After (GS 31) Ally Max or Starane XL can be used. Fungicide applications should now be applied to maintain clean crops.Mobius or Mantra may be used, both contain a triazole and strob in a co- formulated mix. Alternatively Colstar, Midas or Opus Team may be used. If mildew is present add Talius or Corbel.

Spring Wheat

Spring wheat’s are generally more advanced than the barley’s and similar weed control options are available.

Spring wheat’s will benefit from at least two fungicide applications. The first of these should be applied at first to second node (GS 31-32).Where a T1 has not yet been applied Foil and Bravo should be used and Talius added if mildew is a problem.

Potatoes

With planting complete in most areas consideration should now be given to weed control. Products containing Linuron should be used pre emergence of the crop and have residual activity.Gramoxone is not readily available this season and PDQ may be used instead.This is a Paraquat/Diquat mix and can be applied on earlies and seed up to 10% emergence and main crop up to 40% emergence provided the plants are no bigger than15cm high.Sencorex which is both contact and residual may be applied on specified varieties pre emergence up to when stems are 15cms in height. Alternatively Sencorex and Titus may be used up until the main stem is 25cm and an adjuvant such as Activator must be added. Where scutch is a problem in ware Falcon may be used.

Fungicide protection is now underway in many crops and because of the considerable amount of new growth being produced between applications, it is essential the product used be fully systemic to properly protect this new growth. Even crops only emerging must be treated now; they are particularly susceptible to infection once they are through the ground from wind carried spores produced from infected plants elsewhere in the area. Even when treated, these later planted crops are higher risk as they produce more new growth between applications than earlier planted crops, at a time when the level of inoculum in the air is higher.
Shirlan is an optional first blight spray. Although it has no systemic activity, it controls any zoospores that may be in the soil, either from ground keepers or infected seed, and therefore is ideal when the bulk of the product is landing on bare soil rather than foliage. This should be followed up with two applications of Tattoo.