Wet weather, planting delays and hybrid choice

If past experience is anything to go by, as the days pass, growers become more and more uneasy as seed continues to sit in the shed. The question on many minds is, “when is it too late to plant or is it time to switch my hybrid option?”

In recent years, huge advances have been made in breeding medium to short-maturity hybrids that require fewer days from planting to harvest but give excellent yields. Many growers have already made the transition to these hybrids as a result of their stable yield performance, relatively early harvest, greater growth of the following grass crop and a much better overall fit with the whole farm system.

A wide planting window

My colleague Dr Rowland Tsimba did research as part of his PhD thesis into ideal planting windows for maize silage. He showed that the optimum planting dates required to achieve a good yield are much wider than previously thought.

I was taught in my early days with Pioneer that the earlier you get maize in the ground the better. However, Rowland’s work showed that crops planted in November throughout most of the North Island, and at times into December in some warmer North Island regions, can still give good yields of high quality maize silage.

In fact, field and modelling work in Manawatu and Waikato showed that a 91 and 103 CRM Pioneer brand hybrid can be planted until mid-November with an 80% chance of exceeding a silage yield of at least 17.5 tDM/ha (versus 90% for mid-October planting).

Choose adaptable hybrids

In regions where longer-season hybrids are more adaptable, changing to a shorter maturity may actually decrease potential yield. In most situations it might be best to stick with the higher yielding, longer maturity hybrid and then harvest it a bit earlier than normal, e.g. 32% instead of 36% DM. Research shows that the yield of a silage crop harvested at 32% is not much lower than one harvested at 36%. Sticking with the most adaptable hybrid is very likely to deliver greater yields.

Often late planted crops catch up

A two week planting delay may not necessarily translate to a two week harvest delay. Maize seed planted very early into cold, wet soils may take as long as three weeks to emerge. However, with late planting, since soils are much warmer, the crop can emerge as early as five days. For instance, seeds planted in cooler soils, e.g. 12oC, may take 19 days to emerge and only nine days when soil temperatures average 16oC. By the time the plant reaches the silking stage the maturity gap would have narrowed further.

Wait until the soil conditions are right to cultivate and plant. Don’t be too impatient to get your seed in the ground; wait until the conditions are right. Soil crusting tends to be less of a problem with later planting, and the faster growing seedlings can compete better with weeds and have a lower risk of pest damage. Planting should only be done when soils are dry enough to be worked and conditions that promote rapid and uniform emergence to occur are observed.

Achieving uniform planting depth, good soil-to-seed contact and management of in-row crop residue rate highly in determining the success of crop production. Also if your chosen paddock is under water, you may want to think about whether the paddock will drain quickly enough once the rain stops so you can get your crop into the ground. If the answer is no, you may want to think about choosing a different paddock to grow your maize in.

What does the above mean?

I started this article by saying that the rain is pelting down outside. This would have caused some stress before Rowland did his PhD. I am now a lot more relaxed because I know I can safely wait until mid-November before I start getting stressed.

Also comforting is the recent forecast from NIWA which indicates a 55 - 65 % chance of above-average temperatures over the next few months for all growing regions. This scenario usually favours accelerated growth and development in maize crops once they are planted. Here’s hoping.

• Ian Williams is a Pioneer forage specialist. Contact him at This email address is being protected from spambots. You need JavaScript enabled to view it.