Why do leaves yellow at different stages?
Written by
Julia Anderson
Reviewed by
Prof. Samuel Fitzgerald, Ph.D.Yellow leaves signify different things depending on the growth stage and pattern of yellowing. For instance, disease or translocation of nutrients to the fruit means yellowing of lower leaves, which means it is a natural senescence as energy is directed to the fruit. Yellowing associated with new growth may indicate a nitrogen deficiency or overwatering, while a spotted pattern of yellowing over time may be related to disease. The proper diagnosis requires close observation of the location and the timing of the yellowing.
Lower/Older Leaves
- Natural senescence during fruiting as nutrients shift to fruits
- Magnesium deficiency shows as interveinal yellowing on mature leaves
- Normal process when 1-2 leaves yellow weekly during late stages
Upper/New Growth
- Nitrogen deficiency causes uniform pale yellow coloration
- Overwatering leads to yellowing with soft, mushy stems
- Iron deficiency appears as yellow leaves with green veins
Spotty/Uneven Yellowing
- Fungal diseases create yellow halos around brown spots
- Virus infections cause mosaic patterns with distorted growth
- Pest damage like spider mites produces stippled yellow dots
Accurate diagnosis of soil moisture and underleaf is important. Soggy soil indicates overwatering, while progressive patterns indicate deficiency. Use a magnifying glass to examine for pests. Identification saved my roses from spider mites that caused yellow stippling. Proper identification prevents misapplied solutions that add undue stress to the plants.
Prevent yellowing of your plants through specific nutrition and watering procedures. Add nitrogen during the vegetative growth states, but decrease it during flowering. Water the plants thoroughly and at long intervals to prevent root rot. Apply balanced doses of the micronutrients mentioned once a month. My tomato plants have remained green throughout the season since I adapted the feeding according to the stage of development.
Different causes require different rescue techniques. For deficiencies, use foliar sprays for prompt correction. Remove unhealthy foliage immediately, and sterilize your tools. Improve drainage for overwatered plants. I revived yellowing citrus plants by adding iron chelates and adjusting the pH to a suitable level. Always correct basic conditions and not mere symptoms.
Read the full article: 6 Plant Growth Stages Explained Simply
