The first signs are yellow and brown needles on the shoot tips or inside a fir tree. In the early stages, these symptoms only catch the eye of the attentive observer. If the problem that caused it is not addressed, Korean, Colorado, and other popular fir species will eventually lose most of their needles. Instead of coming to terms with the damage, a well-founded analysis reveals the causes. This results in adequate countermeasures so that your fir presents itself in green needles again. This guide explains the correct way to deal with needle discoloration and needle drop on fir trees.
Table of Contents
dryness
What to do: Pour penetratingly.
A lack of water is one of the most common causes of discolored and falling needles on fir trees. Due to a special constellation of countless fine roots and thick taproots, damage to conifers often only becomes apparent after many months. Thus, a summer drought may be responsible for yellow and brown pine needles in autumn and winter. A clear indication of dryness over a long period of time is the discoloration of the needles from the inside out. If you can identify this cause for the problem, take this countermeasure:
- Water the dried fir repeatedly and thoroughly
- Water every 3 to 4 days for a period of 14 days
- Run the water hose for at least 30 minutes on each pass
If the lack of water triggers the symptoms, there is an immediate need for action. In winter, however, please wait for a mild day. In summer, preferably water in the early morning or in the evening, but not under the blazing midday sun.
waterlogging
What to do: Stop watering and tilling.
The counterpart to ball dryness is waterlogging. Your fir tree wants even soil moisture and reacts to extreme fluctuations in one direction or the other with discolored leaves and needle shedding. Since the symptoms are the same, please check carefully which trigger you are dealing with. If the finger test indicates a wet floor, stop the water supply immediately. Waterlogging is always accompanied by a lack of oxygen. Subsequent tillage gives the stressed roots air to breathe again and regulates the problem of yellow-brown, falling needles in the long term:
- Dig up the soil around the roots
- Mix half of the excavation with compost, sand and fine grit
- Distribute the optimized substrate on the tree disc
- Just press down lightly and don’t water
Are you struggling with waterlogging on a particularly valuable fir tree or in a larger stock of trees? Then professional tillage according to the TFI method comes into focus. With special machines, the soil is deeply loosened and aerated without causing damage to roots or supply lines. A special substrate is injected into the soil to give life to the flagging soil. A single treatment is enough to restore the natural soil structure, after which the affected fir trees recover from discolored needles and defoliation.
Frosttrocknis
What to do: water in winter when there is a frost.
Gardeners use the technical term frost dryness to describe a winter problem that affects all evergreen plants and is therefore also relevant for fir trees. Conifers evaporate moisture through their needles at any time of the year, depending on the temperature and light conditions. If severe frost dominates in winter, the trees can no longer absorb water through their frozen roots. If there is no snow cover that provides water, your fir is threatened by drought stress. This is especially true when the sun shines from a cloudless sky. This weather is known as frost for good reason. Now give your conifer a helping hand so that it doesn’t end up without its needles at the end of winter. How to act correctly:
- Water fir trees when there is a frost
- Ideally, wait for a frost-free day to water
- Use normal tap temperature water
Please do not heat the irrigation water. The sudden increase in temperature causes the tissue cells in the roots to burst with irreparable consequences.
Improper nutrient supply
What to do: Have a soil analysis done and fertilize properly.
Fir trees respond to a lack of nutrients and over-fertilization with yellow-brown needles and falling needles. If the gardener concerned asks ten like-minded people what needs to be done, he will receive ten different answers. We therefore recommend trusting in the competence of a special laboratory and ordering a soil analysis. For this purpose, you take soil samples from various places around the fir, mix them together and send them in by post.
With the written result you will receive qualified information about the soil quality as well as concrete recommendations for the right nutrient supply. A meaningful soil nutrient analysis is already available for a price of 45 to 49 euros. The complete package of nutrient and pollutant analysis usually costs no more than 79 euros. The investment is worth it, because you and your fir are spared the imponderables of fertilizer experiments.
lice of all kinds
What to do: Fight with ecological means.
Numerous aphids target conifers in order to extract vital plant sap from the leaves. Some of the parasites have specialized, like silver pine aphids. In most cases, the pests are not choosy and prefer to colonize the soft needles of all fir species. Their shameful doings can only be recognized by the after-effects when the needles turn yellow and brown. Mealybugs and mealybugs sometimes reveal themselves through cotton-like coverings or extremely delicate webs. If you are dealing with aphids, the leaves will first curl up as a result of the sucking action, then discolour and fall off. How to fight lice on fir trees with natural means:
- In the early stages of infestation: repeatedly spray the tree with a powerful jet of water
- Prepare a solution from 1 liter of water and 30-40 grams of curd or soft soap
- Treat louse-infested fir trees with the soap solution every 3 days
The effectiveness of soapy water against lice has been proven so well in practice that you can now buy the solution in stores as a ready-to-use spray. Ecological agents based on rapeseed or neem oil have also had good control successes.
plant shock
Here’s what to do: Slather up.
After planting, the needles of young fir trees turned yellowish-brown, spreading from the tips. If the damage is not stopped, all the needles will fall to the ground by spring. The cause is the stress associated with the removal from the tree nursery and the planting in the garden. Primarily affected are bare-root firs, whose shortened roots cannot transport enough water. Since the needles are already evaporating copious amounts of moisture, the water deficit ultimately causes the dreaded needle shedding. How to act knowledgeably:
- On bare-rooted young firs, reduce the planting cut at the roots to a minimum
- Water regularly and thoroughly for the first few weeks after planting
- Let the water hose run until the floor no longer absorbs moisture
Resume the water supply in the winter when there is no snow and rain. Drought stress as a result of frost brings newly planted fir trees to the edge of their load limit more quickly than is the case with well-rooted, older specimens.
Natural needle fall
What to do: be patient and water more moderately.
Fir trees delight us with their green needles all year round. This attribute does not imply that the individual leaves have as long a lifespan as the tree itself. In fact, needles fall off and are renewed after 9 to 11 years. Before that, the affected leaves turn yellow because their remaining nutrients are shifted to the inside of the tree. This process is usually imperceptible. After a hot, dry summer, not only do the oldest needle crops occasionally drop, but also younger generations.
If you can rule out location problems and maintenance deficits as causes, you will be confronted with this natural phenomenon. Special countermeasures are not required. Depending on the extent of the needle shedding, reduce the amount of water poured since fewer needles will give off correspondingly less moisture.
Conclusion
Helping a yellow-brown fir tree to regain its green needles is a special challenge for every home gardener. Different triggers cause similar symptoms, making countermeasures a gardening balancing act. Drought, waterlogging, nutrient issues, pests and transplant shock all cause needle discoloration and needle drop. Use this guide to teach you about these common causes and give real-world advice on what to do.
