Wendy Madzura
The onset of a new farming season brings with it a new ray of hope for better farming prospects, especially following a good rainy season. It enables one to recoup, reorient and restrategise with the main goal of optimising on productivity levels in any farming venture. It therefore goes without saying that the winter wheat season that has arrived brings with it a blank sheet waiting to be filled up by each farmer at the end of the season depending on the output.

In Zimbabwe, wheat is the second most important cereal crop after maize. The annual wheat consumption for Zimbabwe is above 400 00mt yet wheat imports of around 80 percent are made each year. The import bill for wheat is clearly too high hence farmers are implored to increase local wheat production which will feed into Sustainable Development Goal one (No poverty) and Sustainable Development Goal three (Zero hunger) by 2030.

For any cropping venture to be successful, it is important to START ON TIME. The optimum planting dates for wheat are from the last week of April (in lowveld areas) to the end of May. However, the highest yields are obtained when establishment is done within the first two weeks of May.

Planting on time enables farmers to avoid frost conditions during critical growth stages of wheat like flowering, to avoid high disease and pest pressure during the months of August and September when the crop is in post anthesis stage (grain filling). Early planting also allows the tillering stage to coincide with low temperatures during the month of June. Low temperatures and even frost at this stage, promotes tillering. Observing the planting window allows farmers to harvest their crop before the next cropping season. One of the main advantages of planting on time is that farmers can harvest their crop before the onset of the rainy season. Rain induces sprouting in wheat (Pre-harvest sprouting), thereby reducing the falling numbers which affect the baking quality. Farmers should strive at all costs to establish their wheat seed during the recommended planting window. If the planting window is missed, the consequences can be dire.

Wheat is a temperate crop grown pre-dominantly in winter in Zimbabwe. The nature of Zimbabwe’s rainfall pattern means that wheat is established purely under irrigation. For this reason, a farmer thinking of embarking on a wheat cropping venture needs to carefully assess and determine their irrigation capacity. The total amount of water required to irrigate a wheat crop falls in the range of 450mm to 600mm from establishment right through to harvesting.

The irrigation equipment should be checked and serviced well in advance to avoid hiccups once wheat growing season start. Having ascertained this, the next step is to service all equipment to be used during the establishment of crop. This therefore includes tractors, boom sprayer vicon spreaders or seed drills. It is important to note that poorly serviced or calibrated farm machinery impacts negatively on operations resulting in poor germination, establishment and ultimately crop stand. Irrigation infrastructure must be maintained to ensure there is no water leakages and blockages along the water delivery system.

With that in mind, it is prudent to note that any successful venture starts at the planning stage. A well thought through plan is easy to implement. A good plan is indeed the key ingredient for successful establishment and management of the wheat crop. During the planning stage, farmers should bear in mind that yield is a function of two things; yield per plant and yield per unit area. In the yield matrix there are a thousand reasons for low yields so much that naming them would be close to impossible, however there are only two reasons for high yields.

These are:
1) Good quality genetics/seed

2) Good Agronomic Practices (GAPs)

Starting with the right seed variety suitable for a particular cropping region is key in increasing productivity. When selecting wheat varieties farmers should consider the following factors:

– Yield potential

– Crop stature (short statured varieties are the best)

– Disease tolerance especially to leaf rust disease

– Tolerance to moisture stress

– End use quality, key for the milling and baking industry

They should select modern, innovative seed technologies that couple high yielding capabilities. Wheat yields differ depending on altitude.

In Zimbabwe, white seeded wheat varieties are most commonly grown and have a high yield potential (5t – 10t) depending on altitude with highest yields recorded in the Highveld with altitudes greater than 1 200 meters above sea level (masl) followed by the middle veld (800-1200masl) while lower yields are achieved at altitudes below 800 masl.

Modern wheat varieties are equipped with defensive agronomic traits like a short statured stem and good tolerance to periods of dry spells owing to irregular irrigation. Short statured wheat varieties enable farmers to punch in high plant populations without the risk of lodging.

This results in an increased number of plants per unit area, resulting in an ultimate increase in yield. Modern wheat varieties on the market include SC Select, SC Serena and the traditional workhorse SC Nduna.

For farmers to unlock the genetic potential of good wheat varieties on the market, there is need to employ Good Agronomic Practices that start with soil conditioning and land preparations. Soil conditioning is best achieved after soil sampling is conducted to ascertain the state of the soil in terms of soil pH levels and the soil nutrient status. Soil testing ensures effective conditioning and gives a custom made fertiliser recommendation. Soil conditioning is done during land preparation to incorporate the soil with the recommended soil conditioner as stipulated by soil analysis – mainly liming. Land preparation should be done until a fine tilth is obtained to promote good seed to soil contact. Good seed to soil contact results in a high germination percentage resulting in a good crop stand.

Once soil conditioning and land preparation is done, the next step is to irrigate to field capacity before planting or soon after planting. This gives good germination of the wheat seed. The seed rate for wheat depends on the method of planting to be used. When a precision, well calibrated tool like a seed drill is used the seed rate ranges from 110 to 125 kg per ha, while 125 to 135 kg per ha is used when using a broadcasting tool like a vicon spreader. Other farmers are establishing at higher seed rates, however we recommend that a proper cost benefit be done to understand the cost implications of increasing the cost of production on the productivity level to be obtained.

Farmers are encouraged to come in with a light irrigation or light disking at four to five days after planting particularly in soils with a high silt content to break the crust layer formed on the surface of the ground. This layer may affect germination of the wheat resulting in a poor crop stand.

Once germination is complete, farmers should starve their wheat crop of irrigation water to promote tillering and initiate the development of crown roots. This critical stage is termed “hardening” and it differs for sand soils and clay soils because of differences in water holding capacity. In sandy soils hardening can last for about 10 days and 14 days in clay soils. The aim is to strengthen the wheat seedling and not force them into permanent wilting, hence farmers should exercise caution during this stage.

Once hardening is complete the crop should be irrigated first before any operation is conducted to avoid further stressing the crop. Top dressing fertiliser is then applied at a rate of 350 to 500kg/ha of Ammonium Nitrate (34,5 %N AN) or Urea (46%N). It is recommended to apply top dressing fertiliser in two splits especially in sandy soils.

Topdressing can be applied at four to six weeks after sowing. After top dressing post emergent herbicides are applied depending on weed spectrum to reduce competition. Farmers are encouraged to read labels on various herbicides prescribed for wheat in order to apply the right amount, at the right time for the targeted weed spectrum. Regular scouting is a MUST to determine insect pest problems before they reach economic threshold levels. Common insect pests in wheat include aphids (tillering up to grain filling stages) and bollworms (post anthesis up to maturity). It is important to note that insect and disease pressure increases as temperatures become warmer during the months of August and September hence adhering to recommended planting dates becomes paramount.

The bottom line in any cropping programme is the return per dollar invested (profit margin), therefore farmers should strive to optimise on productivity to push up the output value which is the yield per unit area. Wheat is a crop of economic importance in Zimbabwe and as such, farmers with irrigation are encouraged to venture into wheat farming. The winter wheat season is upon us, let us gear up and hit the ground running.

Start on time and start with the right seed.
*Wendy Madzura is an agronomist