This article was published by Michigan State University Extension. Yellow, stunted alfalfa may not be entirely due to drought. Photo 1. A severely stunted and yellow alfalfa field impacted by both very high potato leafhopper numbers and drought. Cutting of the alfalfa followed by scouting of regrowth is recommended in such cases.
Photo 3. A potato leafhopper adult next to a penny for size comparison. Nymphs are similar in color and shape, but smaller and lack wings. Threshold levels of potato leafhoppers are not often detectable from a distance.
This field averages just under 8 inches tall with 1. Hopper burn is not yet obvious on individual plants. The use of a sweep net is recommended to sample potato leafhopper populations in alfalfa.
Photo credit: Fred Springborn, MSUE Alfalfa thresholds are based on a combination of the number of potato leafhoppers per sweeps and the height of the alfalfa. Did you find this article useful? Please tell us why Submit. Haul manure? Learn More. Potassium fertility impacts hay and pasture performance during drought. There's a good chance that nothing is needed and the situation will improve on its own.
Good drainage is critical. Usually as air temperatures warm and the soil dries and aeration improves, the problem is likely to correct itself. The same is generally true with N deficiency, that is if the bacteria is present for re-inoculation - the plants turn green again when the weather warms up and drainage occurs, if there is rhizobium bacteria available.
While it is difficult to predict the weather and rain events, it is especially important to avoid over-irrigation on these types of soil heavy soils with a high pH and slow drainage.
You are currently not signed in. If you have an account, then sign in now! Anonymous users messages may be delayed. Name required. E-mail required. Yellowing of alfalfa leaves in the springtime - Do you know what this is? Author: Daniel H Putnam Author: steve orloff. Comments: 6. When we used to flood irrigate we would often have very much the same condition. Even with sprinklers if pooling happens the alfalfa will yellow on us in some of our fields.
Especially our fields that are mucky silty clay loam, have water tables of inches, and classified as poorly drained by NRCS Web Soil Survey My vote is too much water.
This yellowing is caused by bicarbonate induced iron chlorosis. I have observed this problem often, since my undergraduate studies at Utah State Univ. It seems to occur especially in alkaline soils above a pH of 8. Great to have you confirm the iron chlorosis, Vern. I've seen this symptom also on high pH soils during wet cool periods on heavy soils.
Soil compaction. Wet soils this spring during preplant operations or hay harvesting operations can result in severe compaction in some fields.
Check for soil compaction by digging and examining both root systems and soil structure. If the compaction is so severe that the taproot cannot pass through the compacted zone, yields will be reduced significantly and plowing and replanting might be the only option. Remember, it is much easier to prevent than to alleviate soil compaction.
Potash deficiency. High quality alfalfa removes a large amount of potassium from the soil each year. Soil test K levels should be monitored closely and fertilizer K should be applied whenever it is recommended. Maintaining soil test levels and preventing soil compaction will help to assure maximum productivity and stand longevity. Root rots. There are a variety of root-rotting diseases of alfalfa that are favored in the saturated soils.
The most damaging is Phytophthora root rot; which can attack any part of the root system of plants of any age. Aphanomyces and Pythium organisms are also known to attack the fine feeder roots of mature plants of alfalfa when soils are saturated.
Always select varieties with R or HR ratings to Phytophthora and Aphanomyces root rots when seeding alfalfa in Kentucky. Unfortunately, there is no known resistance in commercial cultivars to Pythium infection, but improving soil drainage and minimizing soil compaction will help with all three diseases.
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