Family Flower Pest and Disease Control

Author: Feng Tianzhe / Country: Mainland China
Publisher:
Publishing Date: 2000-04-01
Features: It occurs 1-2 generations per year, with the mature larvae overwintering in protective cases on branch tips. In Jiangsu, pupation occurs in April-May the following year, and adults emerge in May, mating and laying eggs. After hatching, larvae first spin silk to build cases, then feed, hiding their bodies within the cases. They mostly feed with their heads and chests extended outside the cases in the morning, evening, or on cloudy days. Young larvae feed only on the lower epidermis and mesophyll, leaving transparent yellowish-brown patches on the upper epidermis. After the third instar, they chew holes in leaves, and by the fourth instar, they can consume entire leaves, tender shoots, branch bark, and fruits.
Control Methods: Promptly remove and destroy protective cases; spray 90% dichlorvos at 1000 times the concentration. Due to the protective cases, insecticides are difficult to penetrate, so the dosage should be increased by about 1.5 times compared to other pests. When spraying, ensure the undersides of leaves and protective cases are thoroughly moistened. The best time to spray is before 9 a.m. or during feeding hours in the evening.
5. Scale Insects Affecting Camellia
The main scale insects affecting camellia include the Japanese wax scale, red scale, and netted scale. The female adult of the Japanese wax scale has a waxy shell about 4 mm long, elliptical, white to grayish-white, with (tortoiseshell-like) concave lines on the surface, a central convex area, and 8 rough protrusions around it. The female adult is 2.5–3.5 mm long, flattened, with a convex back covered in a waxy scale, and is purplish-red. Nymphs are elliptical and relatively flat, orange-yellow or pale orange (Figure 21). It has one generation per year, overwintering as fertilized female adults on branches. Eggs are laid under female abdomens in May of the following year, and nymphs hatch in early to mid-June, mostly infesting new shoots, with a few on leaves. Male insects primarily feed on leaf sap, while female adults mainly damage stems and branches. Males pupate in September and emerge as adults in September–October, mating with females before dying. It is important to spray pesticides like phosalone when nymphs first hatch. Spraying should be uniform and thorough. If the waxy shell has formed, spraying is less effective.
() Jasminum
Jasminum leaves are bright green and glossy, with golden flowers scattered among them. Though small, the flowers have a strong fragrance, and the flowers can be used to make tea or extract essential oils.
1. Anthracnose
This disease occurs on leaves, petioles, tender shoots, and stems, but is most common on leaves. Initially, leaf tips turn brown and expand inward, covering 1/3 to 1/2 of the leaf surface. Lesions have distinct margins. When petioles are affected, the diseased parts turn brown and spread to the leaves, with the main vein, lateral veins, and even entire leaves turning brown sequentially. During the disease progression, leaves and small petioles continuously fall off, eventually leading to the entire plant losing its leaves and branches drying and dying.
Control Methods: Promptly remove and destroy diseased leaves and dead plants. Immediately prune and destroy diseased leaves or petioles. After infection, spray 70% thiophanate-methyl at 800–200 times the concentration. Use well-ventilated, moisture-retaining materials for packaging during transport.
2. Black Spot Disease
This disease often occurs under high humidity and poor ventilation, often accompanying scale insects. Irregular black-brown spots appear on affected leaves and tender shoots. In later stages, the affected areas are covered with a black, sooty substance, requiring attention for control.
3. Stem Rot
This disease affects the stems of jasminum. Initially, small black spots appear, expanding into linear, brown spots. Several spots often merge into a ring around the stem, eventually causing the entire plant to die.
Control Methods: Promptly remove and destroy diseased plants. In the early stages of infection, spray 70% thiophanate-methyl at 800 times the concentration.
4. Scale Insects Affecting Jasminum
The main scale insects include the red scale and soft scale. Female adults and nymphs cluster on the undersides of leaves and branch tips, feeding on nutrients, causing branches and leaves to turn yellow and die. They can be manually removed or controlled with pesticides.
() Jasmine
Jasmine leaves are vibrant green and evergreen. In summer and autumn, it blooms continuously, with flowers as white as jade and a strong fragrance.
1. White Rot
After infection, a layer of white mycelium appears at the base of the stem near the ground, causing the phloem to rot. The plant wilts and dies. In later stages, mycelium aggregates into sclerotia, initially white and spherical, soft, but gradually turning yellowish-brown, resembling rapeseed. Affected plants grow stunted, branches and leaves wilt, flower buds develop poorly, become shriveled and red, and even the entire plant dies.
Control Methods: Refer to peony white rot.
2. Brown Spot Disease
This disease primarily affects young, tender shoots and leaves, with heavier infections in hot, humid seasons. Dark brown spots appear, and leaves gradually turn black and die, or entire branches die. Refer to the previously mentioned brown spot disease for control.
3. Stem Rot
This disease affects the base of jasmine stems. Initially, water-soaked, brown spots appear on the diseased areas, expanding longitudinally into stripes with dark brown edges and grayish-brown centers. In later stages, the affected areas rot, split vertically, and develop black, small spots.
Control Methods: In the early stages of infection, apply 70% thiophanate-methyl to the diseased spots. If the disease is severe, promptly remove and destroy the diseased plants.
4. Blue-eyed Hawk Moth
The adult moth is 26–27 mm long, dark gray with slight green and brown tones. The hind wings have a large, eye-like spot with a purple-black outer ring and a blue-black center. The larva is 72–85 mm long, green to blue-green, covered in yellowish-white granules, with yellowish-white diagonal stripes on both sides of each segment from the first to the eighth abdominal segment. Larvae feed on leaves, and during peak outbreaks, they can devour entire new shoots and leaves. It has 2–3 generations per year, overwintering as pupae. Adults emerge in May, are strongly phototactic, and mostly lay eggs on the undersides of leaves. After hatching, larvae disperse and feed from June to August, severely affecting ornamental quality and fresh flower quality.
Control Methods: Combine with regular management to manually catch larvae. In the early instar stage, spray 90% dichlorvos at 1000 times the concentration.
5. Jasmine Leaf Moth
The larva spins silk to tie branches and leaves together, hiding within and feeding on leaves, flower buds, small branches, and new shoots. Damaged leaves curl and become incomplete, leaving a thin epidermal film and small holes. Severe infestations cause entire clusters of leaves to turn yellow and fall off.
Control Methods: Combine with leaf thinning to remove pupae and infested leaves. Thoroughly remove and burn dead branches and leaves in the garden in early spring. In the early stages of larval occurrence, spray 50% phosalone emulsion at 1000 times the concentration.
6. Jasmine Flower Bud Moth
Also known as the flower core worm. After hatching, larvae bore into flower buds, and one larva can damage multiple buds. This pest can also damage branches, and branches die after being bored by larvae.
Control Methods: Prune and destroy dead branches in early spring to eliminate overwintering larvae. Promptly remove and destroy infested flower buds. Spray 50% phosalone emulsion at 1000 times the concentration.