What is in this article?:
- The ‘summer slump’ period is a decline in alfalfa growth in the low desert areas of the West.
- The summer slump is tied to high temperatures.
- Increased humidity and high nighttime temperatures are other culprits.
Insects should usually be controlled during the summer slump to reduce stress on the plant and maintain crop quality. Insects - especially sap feeders including the three-cornered hopper, potato leafhopper, and lygus - reduce crop growth and contribute to low yields.
The sap-feeding potato leafhopper injects toxins in plant tissues which can reduce alfalfa yield for one or two cuttings in the late summer and early fall.
Leaf-chewing insects, including alfalfa caterpillars, can contribute to lower yield, quality, and increase the summer slump by reducing the proportion of leaves in the hay.
Non irrigation during the summer slump and no insect control are an alternative management strategy which may be economical, depending on the costs of water, insect control, and other production inputs, plus the value of the hay produced.
However, the control of multi-host insects (lygus, potato leafhopper, and stink bugs for example) in alfalfa may be necessary to avoid population build-ups and movement to other crops.
Any disease has the potential to contribute to the negative effects of summer slump. Diseases, including Stemphylium and Cercospora, result in leaf loss and lower hay quality. Rhizoctonia and other diseases which impact the root may compromise the ability of the crop to take up water and contribute to reduced yield during the summer slump.
The chemical control of diseases in alfalfa is generally not economical. Avoidance through good sanitation of equipment and the elimination of water standing for more than 24 hours are recommended to reduce the risk of plant pathogens.