The Reasons for White Spots on Camellia Leaves During Bloom
White spots suddenly appearing on camellia leaves during the blooming season are a common issue that troubles many gardening enthusiasts. These white spots not only affect the ornamental value but may also indicate a health crisis in the plant. This article deeply analyzes the causes of white spots during the blooming period through three sets of real comparison photos and provides targeted solutions.
Analysis of the Three Major Causes of White Spots on Camellias
Characteristics of Powdery Mildew Invasion
As a representative of fungal diseases, powdery mildew is most likely to outbreak when humidity is above 70%. Initially, star-shaped white spots appear on the leaf surface, which can develop into a powdery mycelium layer within 5-7 days. This pathogen spreads through spores, especially infecting new tender leaves, and in severe cases, can lead to abnormal flower bud drop.
Identification of Scale Insect Damage
This type of piercing-sucking pest prefers to gather on the back of leaves, with their honeydew诱发ing sooty mold. The white spots caused by pest damage are irregularly distributed, and careful observation can reveal 0.5-3mm brown scales. Spring and autumn are the peak seasons, and poor ventilation can exacerbate the pest problem.
Symptoms of Rust Mite Damage
This micro-pest, only 0.2mm in size, mainly attacks the leaf flesh. Initially, pinpoint white spots form, and as the pest population increases, the white spots expand into net-like cracks. In high temperatures and dry environments, their reproduction rate accelerates, completing a generation in just 7-10 days.
Comprehensive Management Plan for Camellia White Spots
Physical Control Measures
Remove and burn diseased leaves immediately, and disinfect pruning tools with 75% alcohol. For scale insects, a cotton swab can be dipped in diluted medical alcohol (10 times) to spot-treat, combined with a high-pressure water gun to wash the back of the leaves.
Biological Control Techniques
Introduce ladybugs to control scale insects, and release predatory mites at a ratio of 1:50 to control rust mites. In the early stages of powdery mildew, spray a 1:10 milk solution to use milk protein to form an antimicrobial film.
Chemical Agent Selection
For powdery mildew, use a 25% azoxystrobin suspension at 1500 times dilution; for scale insects, use a 22% thiamethoxam·alphacypermethrin suspension; for rust mites, use a 5% abamectin emulsifiable oil at 3000 times dilution. Apply pesticides avoiding the full blooming period, with an interval of 7-10 days for 2-3 consecutive times.
By conducting regular inspections, scientific maintenance, and precise control, not only can existing white spot issues be eliminated, but a long-term disease resistance mechanism for camellias can also be established. It is recommended to apply seaweed fertilizer every quarter to enhance the plant's resistance to stress, maintain a ventilated and well-lit environment, and allow camellias to continue blooming with health and beauty.