Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.
Is your crop uniform from end-to-end and side-to-side in each house? If plants are smaller at one end, it usually means a temperature difference from end-to-end. However, while side-to-side differences can be due to temperature, check your booms or overhead watering system. I’ve noticed more than a few partially plugged nozzles this spring, usually due to buildup of calcium carbonate or calcium bicarbonate. The growers are usually puzzled by the buildup because they are adding acid to reduce bicarbonate in their water, but, when asked, admit that they hadn’t tested their water this spring and were adding the same amount of acid as last year. When this season’s test came back, the bicarbonate levels were significantly higher and the amount of acid needed to be increased. Be aware that drops in bicarbonate can also cause problems even if your nozzles don’t plug. Low bicarbonate levels increase the probability of sudden pH drops because there is little buffering, so acid sensitive crops such as geraniums can be at risk.
reason for non-uniformity in watering is worn out nozzles. Water is
abrasive, and even ceramic nozzles wear out eventually. I can’t
determine flow rates by looking, and even small differences in flow from
nozzle-to-nozzle can influence plant growth, especially when the
weather warms up. It’s too late to check your nozzles after the crop
shows differences, so take a little time now to put containers under
each nozzle, run the system for a short time and then measure the
variation in the amount of water applied.