Specialist trials highlight needs of 2nd wheats
Getting second wheats to
deliver economically viable
yields will be a key issue
for many growers in the
coming season. Here we
find out from one of the
nations top crop experts
just how much difference
variety choice and crop
husbandry can make
FOUR years of comparative trials with second and subsequent wheats on the Yorkshire Wolds leave Allied Grain Fishers technical manager Jim Carswell convinced that UK growers must plan and manage such crops much more carefully.
The trials show just how differently varieties perform in the different rotational slots and how variety choice and management can best be fine-tuned to maximise returns.
"Since we started assessing varieties as second and subsequent wheats at Haywold in 1996/97 weve recorded major differences in their relative performances," he says.
"Back then varieties like Brigadier and Hereward, which were comfortably outyielded by Buster and Riband as first wheats, turned the tables as third wheats. More recently, in our 2001 trials, weve seen particularly interesting differences in yield ability, if not rank, between leading RL varieties." (Table 1.)
"The contrast between a variety weve found to perform relatively well as a non-first wheat, like Option, and one which tends to be at a greater disadvantage in this slot, such as Claire, was particularly marked."
In the first wheat trials Option outyielded Claire by 0.55t/ha or 5%, but the gap grew to 1.14t/ha or 14% in the second wheat slot.
Although the first/second wheat yield differences at Haywold exceed NIAB averages, Mr Carswell says the variety trends are similar and that the trial results reflect the scale of the second wheat challenge facing commercial growers.
"Higher levels of foliar and stem disease, lower background levels of nitrogen, later drilling and more trash, plus the build-up of take-all, means everyone needs to plan and manage their second wheats very differently from first wheats if they are to optimise performance," he stresses.
The blame for much of the relatively poor performance of non-first wheats in the north has traditionally been laid at the door of take-all and eyespot, provided foliar diseases are well controlled.
Despite every effort to maximise eyespot, including intensive inoculation, the disease has never really developed and responses to treatment have been disappointing.
By contrast separate take-all trials in 2001 showed responses of up to 1.47t/ha to fungicide Latitude (silthiofam), underlining the extent to which this disease is a problem.
"The fact that we cant totally eliminate this disease, even with Latitude, means two things for second wheat planning and management. First, in addition to using the new seed dressing, we need to take as many complementary agronomic steps to control take-all as possible. And second, we must accept that second wheat yields will be lower than first wheats and try to make up for this in every way we can."
In improving second wheat agronomy Mr Carswell has no doubt that early sowing should still be avoided. In his 2001 take-all trials seed treatment improved yield by an average of 0.93t/ha in September sowings, with a further rise of 0.36t/ha from delaying drilling until October (table 2).
His experience also reinforces the importance of applying more nitrogen earlier in the spring to boost root growth. Soil conditions permitting, he recommends 40kg N/ha in mid/late February, around a month earlier than normal with first wheats in the area.
But variety choice offers the greatest scope for improving second wheat performance, Mr Carswell believes.
"Some varieties certainly seem to perform better than others in the second wheat slot. But I believe the first decision needs to be made on the target market. It makes sense to look for a premium for quality to make up for the inherently lower yield potential. All the more so because the lower yields mean less protein dilution and more chance of getting a better quality spec.
"Those who can rely on getting a bread-making sample from the ground in question should be prioritising Group 1 wheats. But Group 2s are potentially better bets where theres significant doubt over making the full bread spec.
"That is especially so with the new generation of varieties that can yield as well as most feed wheats and have an excellent potential for generating premium quality grain from a range of sowing dates, without the high N inputs demanded by some Group 1s.
"The alternative, of course, is to go for Group 3 or 4 wheats," he adds. "If that is the case growers should choose the highest yielding varieties available to maximise returns from the feed price. And, crucially, they need to choose them on the basis of their local performance as second wheats rather than merely on national headline figures.
"In specific RL variety terms, at Haywold, Id have to favour Malacca amongst the Group 1s. Option stands out as a Group 2, Consort would be my first choice Group 3, while Savannah, Genghis and Napier are obvious Group 4 contenders. In other areas of the country, though, the priorities may vary" *
Table 1: RLwheat variety performance (Allied Grain Fishers, Haywold 2001)
Second wheat Second wheat First wheat First wheat
ranking yield % * ranking yield % **
Option 114 Savannah 122
Savannah 106 Option 119
Consort 106 Consort 118
Napier 100 Napier 118
Malacca 100 Equinox 118
Claire 100 Madrigal 117
Madrigal 89 Claire 114
Equinox 87 Malacca 111
Hereward 83 Hereward 104
*Percent of trial mean (8.44t/ha). **Percent of untreated mean (10.83t/ha).