Dig for seed where there are skips to determine if seed is present or not. If there is no seed, check planter settings and maintenance prior to next planting.

Check for damaged and/or partly eaten kernels. If the problem is severe and widespread, consider replanting worst affected areas. In future consider preventative measures including seed treatments, baiting and/or population control.

In the future either "plant to moisture" if the soil is dry, ensure adequate moisture is present before planting or irrigate after planting.

In the future check seed-soil contact when planting, adjust down force, press wheels and/or residue managers if necessary. Revise tillage practices or soil conditions at cultivation if the soil is cloddy.

If suspected dead seed is greater than 10% request an inspection from your seed supplier.

Cold, wet soil.

Residual herbicide damage or excessive fertiliser too close to seed.

If suspected dead seed is greater than 10% request an inspection from your seed supplier.

Check seed treatment used, this should include fungicide; but several species of bacteria may also be involved. Seed rot tends to be prevalent in cold or very warm, wet soils, and/or where high rates of raw manure have been applied.

Seed may have germinated but roots appear stunted or burnt. In-furrow (pop-up) fertilisers with high salt indexes are the most risky; it is safer to apply these fertilisers 5 cm below and 5 cm to the side of the seed.

Slugs and black beetles can chew the growing point (shoot meristem) beneath the soil. Closely inspect the damaged seedlings for signs of chewing.

Crusted, cold or cloddy soil. A cloddy soil can allow light to penetrate the soil disrupting normal “spike” emergence.

Aim for 4-5 cm planting depth with good seed-soil contact; only plant shallower if the soil is already damp and rain is forecast in the first few days after planting. Do not plant shallower than 3 cm as there is an increased risk of nodal root development problems during the establishment phase.

Can be caused by pre-emergent herbicides including acetachlor and metolachlor especially in very light, or cold/wet soils where seedling emergence is delayed; preplant incorporation of these herbicides may increase risk in some situations (e.g. light and/or cold/wet soils).

Cold, dry, wet, cloddy or crusted soil.

In the future pay attention to seed depth placement in different areas of the field while planting, especially where soil conditions change.

Usually caused by excessive planter speed and/or uneven soil surface. In the future check seed depth uniformity during planting and adjust planter/speed as required.

In the future check seed-soil contact while planting when soil conditions are changeable and adjust planter set-up if necessary.

Talk to your seed supplier if you are concerned and other causes are unlikely.

Common culprits are pheasants, pigeons, pukekos and rats. If the problem is severe and widespread, consider replanting. In the future consider preventative measures including seed treatments, baiting and/or population control.

Cold, dry, wet, or compacted soil.

Check for patterns in row vigour/growth across the field. Are they systematic and related to planter passes? Is the fertiliser blocked, placed too close or distant from the seed furrow? Starter fertiliser should be placed 5 cm below and 5 cm to the side of the seed furrow. In the future check fertiliser placement during planting, focusing on headland/turning exits to help identify issues.

Check for patterns across the field, focus on sprayer overlaps around headlands and uneven contour. Check the chemicals used, label application rates and timing.

Usually associated with other symptoms including discoloured leaves (see Discoloured leaves ). If a deficiency is suspected, collect plant tissue samples to determine the nutrient balance.

Check for insect and/or slug damage. Apply remedial action if necessary.

Check uniformity of seed depth and root development. Planting too shallow can affect nodal root development especially in dry, loose, cloddy soil and/or windy conditions. In the future ensure a correct and even planting depth is achieved and adjust speed and downforce if necessary.

Talk to your seed supplier if you are concerned and other causes are unlikely.

The most common nutrient deficiencies are N, P, K, S, Mg and Zn at this stage (see Leaf Abnormalities for specfic symtoms). Usually, N, P, K, S and Mg availability can be adequately forecast in soil tests. Collect plant tissue samples from affected and normal areas to analyse for a deficiency. Apply remedial action if the deficiency is widespread and necessary.

This includes frost and near frost events. Frosted plants will appear burnt, pale and weak. Check the growing point (below the ground) for damage. Usually worse in low-lying areas. Plants usually recover providing the frost is not too severe or late. Widespread, severe frost at V4 or greater may require replanting. Quantify the affected area and severity and seek advice before making the decision to replant.

Cool nights and warm days promote shoot growth over root growth which can limit nutrient uptake, making shoots appear pale and/or unthrifty.

Perfect conditions for nutrient losses (leaching and denitrification). Collect tissue samples to determine any deficient nutrient(s) and try to correct any deficiencies if it is economically viable and possible.

Affects root growth and nutrient uptake. In the future reduce and alleviate compaction with deep ripping and limit wheel traffic before and after planting. There are a multitude of crop management systems that can minimise the risk or severity of compaction.

Diseases such as anthracnose can cause yellowing and blotchy patches (lesions) on the leaves of young plants. Most prevalent in wet conditions, particularly ponded areas. Plants will usually recover but may be prone to stalk rot during the grain drydown period. Monitor affected areas during this period.

Chewing may be accompanied with chlorosis (yellowing) or other pigmentation (e.g. purpling) and general unthriftiness. Apply control measures if damage is widespread. In the future consider the merits of preventative control measures.

Leaves may appear pale, bleached and/or scorched. Symptoms are usually worse in overlap areas so focus on headland and contoured areas. Always check chemicals, the compatibility of mixtures used and application rates/calibration before spraying. Some herbicides can interact with some insecticides including seed treatments so again, check compatibility before spraying.

Leaves can appear pale, bleached and/or scorched. Check roots for signs of damage as well as starter fertiliser placement and application rate.

Includes tyre damage and machinery. Check roots and shoots for damage. If the damage is significant or widespread ask the question “how do we avoid the same problem in future?”.

Some hybrids are naturally darker or lighter in colour than others. Providing the crop looks uniform with healthy roots and shoots, subtle differences in colour should not be of concern. Take notes on differences in colour between hybrids for future reference.

In dry conditions plants may take on a pale and/or greyish tinge, which is usually accompanied with leaf rolling; particularly during the heat of the day (see Leaves rolled ).

Leaf rolling can occur in very hot conditions, even in seemingly moist soil. More often leaf rolling will occur when the soil is approaching the critical soil moisture deficit where water uptake cannot service transpiration requirements. If possible, apply irrigation before this point to avoid reducing nodal root development which may affect yield.

Insects feeding on roots reduces water uptake causing leaves to wilt. Check roots for damage.

By side dressing or weeding implements. Check roots for damage.

Certain pre and post-emergence herbicides can cause leaves to curl or twist. Sometimes this is a temporary phenomenon, whereas at other times the problem can last for weeks, reducing the yield potential of affected plants.

Alternating hot and cold weather induces alternating periods of fast and slow growth, this can cause developing/emerging leaves to become entangled.

This is often caused by crushing of the leaf whorl from tractor tyres etc.

Damage to the leaf whorl can cause leaves to become entangled.

Calcium deficiency can cause leaves to entangle and become laddered. It is rare but collect tissue samples if there is no other logical explanation.

Slugs, Argentine stem weevil (ASW), or cutworm.

Common culprits are hares, stock and birds.

Wind causes abrasion of leaves on the soil surface. Hail damage is usually accompanied with ponding and/or soil splashing onto leaves and into whorls.

Most common on exposed lighter textured (sandy) soils in high wind-run areas.

Most commonly N, P, K, S, Mg and Zn. Collect plant tissue and soil samples from affected and normal areas for analysis. If the deficiency or imbalance is widespread seek advice on remedial action.

Anthracnose (prevalent in ponded areas) or bacterial wilt (prevalent in cool, wet soils).

Spray drift from neighbouring crops or overlaps (check headlands and contoured areas).

Some hybrids are more susceptible to the possible causes of leaf scorching, spotting or striping; and because one hybrid doesn’t show any symptoms this doesn’t mean that another hybrid will be unaffected by a potential causal agent.

Argentine stem weevil (ASW) larvae, cutworm or black beetle. Check for signs of insect chewing above and below ground.

Phythium seedling blight (damping off) or bacterial wilt.

Shallow planted seed may not develop a strong nodal root system and may be prone to falling/leaning. If the problem is widespread consider mounding the soil around the base of the plants to provide an opportunity for nodal roots to develop (effective before V4).

Common culprits are cutworm (plants chopped off) and Argentine stem weevil (ASW) larvae (plants wilt from the growing point with an accompanying hole in the stem at or just below ground level). Cutworm can be controlled by spraying a synthetic pyrethroid while ASW can be controlled by seed applied insecticide Poncho®.

Especially caused by 2,4-D or similar (auxin-type) products followed by a strong wind event. These products can make plants brittle and susceptible to lodging and green snap.

Severe winds can cause plants to fall or snap. If nodal roots have properly developed it is unlikely that plants will fall at this stage unless the soil is very loose and/or wet. More common is green snap where plants snap off above ground level once the stems start to elongate.

Most common culprit is Argentine stem weevil (ASW) larvae but other insects cannot be discounted.

Particularly phenoxy-type products such as dicamba can affect nodal and brace root development. Typically, this is only a problem if applied too late (after V6) or at higher rates. Some hybrids are more susceptible to these herbicides so check tolerance to phenoxy herbicides before application. If concerned ask your seed supplier.

Particularly black beetle.

Commonly caused during side dressing or other post-planting tillage operations.

Planting or field operations when too wet can cause sidewall compaction. Check for horizontally restricted root systems.

Crazy top - occasionally occurs in the Waikato and Northland but is generally rare and control measures are unnecessary.