"SPRING habit" winter cereal varieties (oats, wheat, barley triticale cereal rye) sown in February or March commonly come to head in May, June or July, with time dependent on sowing time, variety and area.
These crops tend to recover slowly and often poorly after grazing.
In contrast, varieties with "winter habit" recovered far better after grazing, are less likely to be adversely affected by frost and retain high quality longer.
"Winter habit" is a characteristic where the head or growing point remains at ground level until a sufficient amount of cold weather triggers plants to change to "spring habit", which means the head begins rising up the stem.
Spring habit varieties have no such delay with heads growing up the stem as soon as tillering occurs.
When animals graze below the developing head, which can be quite early for spring habit types, the tiller dies and new tillers need to reform.
Reforming of tillers can be slow, especially in the middle of winter and if soil water supply is low.
Varieties with "winter habit" vary in their level of "winter habit".
This means varieties with only a low "winter habit" level will transfer to "spring habit" and have heads growing up the stem after a shorter period of cold winter weather than varieties with high levels of "winter habit".
High levels of "winter habit" means heads remain at ground level for a much longer period.
Desirable variety "winter habit" level is largely related to climate and purpose.
For example, if the purpose of the crop is mainly for early sowing and for long grazing time throughout winter and spring, a variety with a high level of "winter habit" may suit best.
A dual purpose role is more likely to best suit a variety with moderate to lower levels of "winter habit".
This allows early sowing with no running to head too early, nor loss of tillers, and a period of 30 to 90 days grazing prior to locking up for grain recovery.
Desirable length of grazing is variable and is not only related to variety type but sowing time (more if early) and seasonal conditions.
Climate also has a big role in choosing how much "winter habit" a variety should have.
Colder areas have varieties "winter habit" satisfied faster, therefore varieties with greater "winter habit" are needed.
In contrast in warmer environments varieties with less "winter habit" are needed, unless used only for grazing.
Varieties with "winter habit" tend to grow slower at first than "spring habit" types.
This slower growth is more than often of little consequence if sowing earlier as the crop tends to make up it with better recovery post grazing in winter early spring.
However, later sown grazing or dual purpose winter cereals may preferably be sown to non "winter habit" types because there is less time to make up for their slower early growth.
Also later sown crops tend to have heads running up the stem slower than when sown early and damage or loss of tillers from grazing, as least for limited grazing duration, is less of a problem.
This is especially the case if crops are not grazed to the ground.
Other factors need to be taken into consideration for choosing grazing or dual purpose crops such as rust and barley yellow dwarf virus resistance and especially for dual purpose ones grain recovery ability after grazing.
But the overriding issue for most areas is to focus on sowing as early as possible as winter feed supply is often very dependent on it.
And it is for early sowing that variety choice is especially critical.
Bob Freebairn is an agricultural consultant based at Coonabarabran. Email Bob Freebairn or contact 0428 752 149.
