Caring to your crop in the course of the first 40 days

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On this article, the primary in a two-part collection, Magda du Toit speaks to specialists in regards to the totally different development phases of a maize plant within the vegetative section, in addition to the essential administration practices to observe throughout this time to attain optimum yield. Recommendation on weed management can be included.

Maize farming: Caring for your crop during the first 40 days
A wholesome and uniform plant inhabitants is vital for optimising yield.
Photograph: Danie Bester

Maize farmers who correctly perceive the expansion and growth of their vegetation are higher in a position to apply the proper manufacturing and administration practices on the proper time, and thereby obtain optimum yield.

Whereas producers haven’t any management over environmental stress situations reminiscent of rain or drought, they’ll mitigate these dangers. For instance, they’ll select a hybrid cultivar, enhance their tillage strategies, enhance the situation of the soil, apply fertiliser, rotate crops, irrigate, and management pests and ailments.

There are two developmental phases within the life cycle of the maize plant: the vegetative section (V section) and the reproductive section (R section). The previous supplies the inspiration for the latter.

Stress at sure essential development phases of maize throughout and after emergence can scale back yield dramatically, says Kobus Lindeque, head of Syngenta’s seed enterprise in Africa.

“To begin with, a correct seedbed and a great, uniform plant inhabitants in the course of the emergence stage is critical for making certain the deliberate yield. It’s vital to observe the suggestions of the seed corporations concerning the precise hybrid in correlation with the world the place the maize is cultivated.”

Lindeque provides that poor or staggered emergence could be problematic. “The longer that seedlings take to emerge, the higher the possibilities are that soil-borne fungus pathogens can penetrate the plant, main to wreck and yield loss.”

Soil temperature larger than 15°C is required for uniform emergence and vigour. Cool soil inhibits root growth and, consequently, moisture and nutrient absorption, slowing growth.

Throughout germination, the stem and development level are 25mm to 40mm beneath the soil floor. Underneath heat, moist situations, seedlings emerge after six to 10 days; beneath cool or dry situations, this will take two weeks or extra. The optimum temperature vary for germination is between 20°C and 30°C, whereas the optimum moisture content material of the soil is about 60% of soil capability.

After emergence, the plant continues to develop via the assorted leaf phases, V1 to VT, every representing the variety of leaves produced by the plant throughout that individual stage (see field for rationalization).

In accordance with Andries Wessels, seed product growth supervisor at Syngenta, the interval from emergence till the V5 stage is essential, and any type of stress positioned on the plant all through this time may have a destructive affect on yield.

“From V3 to V5, the variety of [kernel] rows per ear that the plant will produce has already been decided. This key yield-determining stage is named the switching level, and for the remainder of the season the yield potential can solely be maintained or lowered, relying on the expansion setting. Yield can’t be elevated past the switching level stage, and by V8, the quantity or kernels per row has been laid down.”

From V3 to V5, the expansion level continues to be underground, the place it’s closely influenced by soil temperatures. A low soil temperature can prolong the time between leaf phases, and though injury brought on by hail, wind and frost at this stage has little impact, it may delay the expansion interval by a number of days. As well as, waterlogging whereas the expansion level continues to be beneath floor, particularly when related to excessive temperatures, can lead to important stand loss.

The vegetative section is adopted by the primary stage of the reproductive section (R1), throughout which the silk is fashioned. That is additionally an vital stage, as water and nutrient stress can result in strained growth of the maize ears.

Root growth
Leonard Oberholzer, market growth lead for South Africa at Bayer Crop Science, suggests {that a} soil auger, a spade and a water-filled spray bottle be stored at hand to hold out fast plant root and soil inspections.

The auger will allow you to determine doable soil compaction, and verify the moisture degree and depth of the soil. The spade and spray bottle assist with root examinations. Oberholzer provides that the roots play a elementary function within the growth of the plant, as they permit for the uptake of water and vitamins.

“Climate, soil properties, fertiliser and pestscan affect the expansion and distribution
of the basis system within the soil. Root growth can be a great indication of what’s occurring within the soil. Bodily and chemical traits of soil can affect root growth, and if you happen to discover one thing throughout this stage of the plant’s growth, it should decide additional actions.”

Maize vegetation develop quickly in the course of the first 30 to 40 days after planting, and it’s best to present satisfactory vitamins. That is the time to search for indicators of nutrient deficiency. The vegetation ought to be deep inexperienced in color; purple-tinged leaves might imply the vegetation are affected by an absence of phosphorus, whereas light-green leaves point out an absence of nitrogen.

Leaf samples can verify deficiencies and assist to find out corrective actions and the way a lot of a sure fertiliser it’s best to apply.

When the vegetation are between 4 and 6 weeks outdated, you may apply a high dressing with ammonium nitrate/urea. Maize grown in sandy soil could require a break up high dressing, with the primary half utilized at 4 weeks and the second at seven weeks after emergence.

Weed management
Weeds can considerably scale back maize yield. In earlier analysis, weeds triggered yield losses of as much as 12,8%, regardless of weed-control functions; when the weeds weren’t managed in any respect, losses rose to 29,2%.

Wessels says it is very important begin the manufacturing season with a subject freed from weeds and competitors in order that the seedlings can develop unhindered.

“Weed management is a vital administration apply for maize manufacturing that ought to be carried out to make sure optimum grain yield and help the switching level yield degree. Weed management, particularly within the first 10 weeks after crop emergence, is crucial, as it should scale back the competitors from weeds for obtainable mild, water and vitamins.”

Make use of an built-in weed administration programme, combining cultural, mechanical and chemical strategies. Methods reminiscent of larger planting densities and crop rotation could be included within the programme. If mechanical strategies are used, watch out to not strategy the vegetation too carefully after the V2 stage, as the basis system can simply be broken.

A big selection of herbicides is obtainable for maize. Select a weed management programme to handle these weeds which can be probably the most troublesome to manage.

Acetanilide can be utilized earlier than and at planting, whereas atrazine can be utilized pre-emergence and later within the season. Combining acetanilide at planting with atrazine afterward will guarantee good management of each grasses and broadleaf weeds.

Oberholzer affords the next phrase of warning, nonetheless: “When rainfall is especially late, and also you resolve to replant a land with sunflower, be certain that atrazine has not been utilized to the land earlier.”

With glyphosate-tolerant maize, you may apply accredited glyphosate and registered merchandise to the land with out harming the crop; solely the goal weeds might be killed.
Leaf phases as soon as once more come into play with herbicide functions. When you spray sure herbicides throughout emergence beneath chilly and moist situations, the vegetation could also be broken. Search knowledgeable recommendation in case you are not sure.

Chorus from spraying glyphosate on high of the maize vegetation from the V8 stage onwards or after the event of the sixth true maize leaf, which usually is about 4 to 5 weeks after emergence.

Doing so can injury the expansion level and the pollen, compromising pollination and, consequently, yield. Glyphosate could be sprayed utilizing a increase with drop-arms to direct the spray to the decrease elements of the plant and the inter-row soil floor.

Managing herbicide resistance
With herbicide-tolerant crops, farmers are sometimes tempted to overuse the only herbicide that the crop is proof against. Resist this temptation! Take the time to make use of merchandise with totally different modes of actions. In accordance with CropLife South Africa, the frequent use of an identical mode-of-action herbicide might be the largest issue within the growth of herbicide resistance in weeds.

“Managing resistance is usually rather more efficient than coping with a resistant weed when it turns into troublesome to manage. One of the best ways to proceed is to make sure that a wide range of herbicides with totally different modes of motion are used. This may be carried out in tank mixes the place the herbicides are suitable, or in sequential functions the place they’re not,” advises Oberholzer.

The next easy programmes can be utilized. Observe, nonetheless, that they’re depending on the weeds current, the variety of weeds, and the planting density of the maize:

  • Glyphosate at or after planting, adopted by glyphosate earlier than the sixth-leaf (V8) stage.
  • Acetochlor with a safener at planting, adopted by two functions of glyphosate earlier than the sixth-leaf (V8) stage. The second glyphosate utility might be made after the sixth-leaf (V8) stage whether it is directed away from the funnel.
  • Glyphosate at or after planting, adopted by glyphosate and acetochlor across the sixth-leaf (V8) stage. When making use of herbicide, observe the directions fastidiously and take the required security precautions.

E-mail Kobus Lindeque at [email protected], Leonard Oberholzer at [email protected], or Andries Wessels at [email protected].


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