This column is supplied by Derek Knight (01430) 861988 and David Martindale (01609) 760362, ADAS consultants in East and North Yorkshire

MOST autumn-sown wheat and barley crops are now well bulked with plenty of tillers.

Although plants in many fields are at the early stages of stem elongation, shoot dissection reveals that even the more forward crops in southern and eastern areas are not yet at GS 30 (ear at 1 cm). In this year's large crops, there is really no substitute for splitting the stems with a sharp knife to see where the ear is sited.

A continuation of the mild conditions has led to relatively rapid emergence of winter-drilled crops, with wheat sown in January already at GS 11-12. Across the countryside the increased greenness of both crops and grass has been noticeable during the last fortnight. The forecast of frosts for the immediate future will check some of this early growth and should provide a useful control of early disease build-up, which as yet is not too prominent on the new foliage.

With a continuation of the mild conditions, wheat bulb fly egg hatch has started to advance more rapidly, as shown by ADAS field studies at higher-risk sites in the east and north. Hatch in the north is also starting to advance steadily compared with last week's figure of around 10pc. With increased crop invasion in the north, symptoms of attack are expected to become visible during the next week.

Weed problems in cereals - the highest priority crops for treatment are those that have not yet been sprayed and where the weed size is getting to or exceeding the stage where good control can be expected. Any autumn recommendations that have not yet been applied will need revision of the rates, and possibly the introduction of new active ingredients. The longer the planned January/February applications are delayed, the more feasible it is to combine 'autumn' and 'spring' treatments.

Some wild oats have already started to appear, but it is unlikely that treatment now will give season-long control of later emerging plants. If grass weeds are present and starting to tiller, treatment should be applied as soon as possible and, if necessary, later broad-leafed weed treatments can go on with first fungicides or PGRs. Cleavers have continued to grow quickly in the mild weather. Early treatment with Eagle (amidosulfuron) or Starane XL (fluroxypyr and florasulam) may be justified, especially where patches are affecting crop development.

In the warmer weather, as growth has picked up, manganese deficiency has once again started to reappear on lighter soils prone to producing symptoms.

A kind autumn with crops drilled in good time, and a mild and relatively dry winter have all added up to a situation in which most crops are well established and well developed; this means that for many crops there is no need for the usual early bag of nitrogen in mid-late February.

So far, this winter has been average in terms of rainfall. The drier the winter, the more residual soil N survives and can be used by the next crop. Early spring nitrogen will only add to the shoot numbers - this will increase the risk of lodging and high disease levels which will add to the need for PGRs and fungicides, and may reduce yields. For winter wheat, the target shoot population at GS31 is around 1000-1200/m2 (ie, 3-4 shoots per plant).

Rape crops are starting to make new growth and becoming overall green in appearance as older yellow leaves are lost. Flower buds are present but still well covered. Phoma leaf spot can still be found on the oldest 2-3 leaves, although young leaves are not showing symptoms. There was strong phoma leaf spot activity in the autumn and there is expected to be more limited development in the spring this year.

Where late autumn sprays were applied, levels of phoma leaf spot may be very low. Light leaf spot can be found readily in the north even where autumn sprays have been used. There is some infection in the east and a general inspection of crops is advised before taking further action with fungicides. Light leaf spot is the main threat to yield at this stage and crops at risk are likely to show a general scattering of small patches (foci) of plants with bleached or mealy blotches. Diagnosis will be more difficult if there has been some nitrogen scorch.

For oilseed rape, too much early nitrogen can result in excessive shoot and leaf growth which can cause lodging and poor yields.

Winter bean crops are establishing well and plants typically have 2-4 expanded leaves. Localised slug and rook damage in the east and south has thinned some crops. Most crops have no obvious disease problems.

Updated: 10:15 Thursday, February 21, 2002