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Maize varieties

There are a multitude of maize varieties available. The choice of variety will depend on market requirements, environmental conditions, whether the crop is irrigated and the level of disease resistance required. Varieties are continually changing so ensure you have up-to-date varietal information.

Key to maize ratings

(1) End use

  • S – starch
  • P – processing
  • F – feed
  • Sil – silage

(2) Husk cover

  • TO – tight open
  • TC – tight closed
  • MO – medium open
  • MC – medium closed
  • LO – loose open
  • LC – loose closed

(3) Disease reaction

  • S – susceptible
  • MS – moderately susceptible
  • MR – moderately resistant
  • R – resistant
  • NA – not available

(4) Stalk strength (lodging resistance)

  • very poor
  • below average
  • intermediate
  • above average
  • very good

(5) CRM (cumulative relative maturity, days)

  • 100-112 quick
  • 113-115 medium quick
  • 116-120 medium
  • 121-130 medium slow
  • 131+ slow

Selecting a suitable variety

Time to flowering

Under conditions of adequate soil moisture, mid to slow maturing hybrids will produce a higher yield than quick maturing hybrids. Therefore, growers aiming for maximum yields should consider a mid to full season maturity hybrid. However, where irrigation is limited, a mid-season hybrid may produce more    yield  per megalitre of water. This may also be the case in fully irrigated situations where it is desired to limit the number of irrigations for economic reasons or to plant a following crop to obtain maximum utilisation of seasonal conditions. In dryland environments, commercial full season hybrids    can  handle heat and moisture stress and then respond to a break in the weather.

Within the choice of hybrids available, growers, particularly in dryland situations, may wish to reduce the risk of yield loss caused by unfavourable seasonal conditions by planting a number of hybrids, perhaps with a range of maturities.

Cob height

Cob height tends to be correlated with maturity. Longer season hybrids usually have higher-set cobs than quicker-maturing hybrids. Excessive cob height, greater than 1.5m can be a contributing factor to root lodging (especially if there is wind and rain around flowering), and to stalk lodging (particularly    if  stalk rot has infected the plants). Lodged plants can be slow harvesting and reduce yield.

Husk cover

Husks function to prevent damage from Heliothis (Helicoverpa spp.) larvae, reduce ear/kernel rots (Diplodia, Fusarium) and smuts, and protect the grain from weathering. Therefore, a good husk cover (including tip cover) can be important if insects, disease, and pre-harvest rain are likely to pose threats. However, in areas where    quick  dry-down is necessary because of a short season, hybrids with light, loose husks may be best adapted.

Standability

Standability (resistance to lodging) is important because it reduces harvest losses and grain damage. Many factors contribute to standability including resistance to stalk rots, good mechanical stalk strength and cob height. Most modern hybrids have good standability but some seasonal conditions (e.g.    water  stress during grainfill) can cause serious lodging. Always choose hybrids with good to excellent standability.

End use

Hybrids generally have specific grain characteristics which govern their suitability for particular end uses such as milling for grits, stockfeed, silage or other special purpose uses.

Isolation

All white, waxy and popcorn varieties of maize must be grown in isolation (both in distance and time) from other maize varieties, as pollen from other crops will affect the quality of grain produced by these types. Seed companies or grain purchasers may have specific recommendations that need to be    followed.

Planting maize

Planting times

In southern Queensland, mid-September to mid-October is the premium time. December provides another suitable opportunity, especially for dryland crops. In Moreton, maize is often successfully planted as early as mid- August. Latest plantings in these areas would occur in early to mid-January, due to    likelihood  of disease development in late summer/autumn.

A minimum soil temperature of 12° C is needed at seed depth before attempting sowing in mid-September. Cold conditions after establishment will slow the growth of seedling maize, often causing it´s foliage to turn purple. This is probably due to reduced phosphorus availability at lower soil    temperatures.  However, once temperatures begin to rise again, the crop continues to grow normally. Planting at this time will avoid flowering in mid- summer heat.

December plantings flower after mid-summer heat but may be more susceptible to diseases such as rust, leaf blights and wallaby ear, and perhaps fusarium kernel rots.

Hot, dry weather can kill pollen as it is shed from the tassel, or induce uneven flowering. For example, silk emergence from the cob may be delayed and occur when pollen is no longer being shed from the tassel, resulting in poor seed set on the tip of the ear.