2.3 North America

The monitoring period from January to April 2020 covers the winter dormancy, green-up and flowering stages of winter wheat, depending on latitude. Abundant precipitation has produced generally favorable conditions. In April, a cold snap may have caused some local freeze damage to wheat in some parts. While temperatures were generally warmer than average from January to March, they were below average in April, which in turn may have slowed down growth and development of wheat. However, this has no negative impact on yield. Slow development prolongs the growth period and allows the crop to intercept more light for photosynthesis. 

As a whole region, North America received abundant precipitation (+ 24%) and warm temperatures (+ 0.7 ° C), but photosynthetically active radiation was significantly lower than the average (-8%) for the same period over the past 15 years. Winter wheat reached heading and flowering stages in the south. In terms of the southern Great Plains, the most important growing area of winter wheat, precipitation in Oklahoma, Texas and Kansas was significantly above average, the peak of precipitation occurred in the middle of March and then gradually declined to below-average levels in April (Figure 1). During this monitoring period, the temperature fluctuated greatly in the southern Great Plains. It was above average in March, but dropped to a below-average level by 5 ℃ in April (Figure 2). This delayed crop development. Colorado and Western Kansas were affected by below-average rainfall. The effects are shown in Figure 5, where VCIx is below 0.5 for that region. 

In general, conditions were close to average for winter wheat.

Figure 2.2 North America MPZ: Agroclimatic and agronomic indicators, January to April 2020.

a Spatial distribution of rainfall profiles

b Spatial distribution of temperature profiles

c Potential biomass departure from 5YA

d VHI Minimum

e Maximum VCI

f Cropped and uncropped arable land