What are the common diseases and insect pests of Gerbera? How to prevent and cure it?

African chrysanthemum is an evergreen herb with perennial roots, which is suitable for the environment with warm winter and cool summer, smooth air and plenty of sunshine. So what diseases and insect pests will occur when African chrysanthemum is cultured? How to prevent and cure it?

Stem rot

1. Symptoms and harm

It showed that the leaves were dehydrated and wilted, and gradually turned purple-brown and withered, and it was found that the stem was black, vascular bundles and ducts were blocked, and the root system was normal; this is a soil-borne disease caused by Fusarium, which is mainly invaded by plant wounds and is not easy to cure after occurrence.

two。 Characteristics of the disease

The pathogen overwintered in the soil, and the thick spores survived for many years; spread by water; invaded by the wound. Heavy rain, large amount of water and stagnant water in soil are beneficial to the occurrence of the disease. The disease occurred in the protected area from April to August and occurred in the greenhouse on the annual basis.

3. Prevention and cure method

3.1 cultivation techniques for disease prevention

Soil moisture is moderate, do not suddenly dry and wet; adopt 6 ridges and 1 deep ditch, or dig deep ditch around the greenhouse (areas with high groundwater level); drainage in time after rain, ploughing and other agricultural work do not excessively hurt the root.

3.2 Chemical control

It can be prevented by 75% 3~4kg per mu combined with watering into the root. It was poured with 50% Fuling 800x plus NEB root promoter, and irrigated continuously for 2 or 3 times at an interval of 5 days.

Grey mold disease

1. Symptoms and harm

When the disease is serious, the leaves dry up and die. The disease spot mostly occurs in the leaf margin with waterlogged and brown patches, which are semicircular or irregular after expansion. In the later stage of the disease, the disease spot is yellow-brown, the edge of the spot is purple-brown, and there are rims but not obvious. The petals are brown necrotic spots, elongated or irregular. A gray mildew layer is produced on the necrotic petals at high humidity.

two。 Characteristics of the disease

The bacteria overwintered in the diseased plant or soil, and the sclerotia survived for many years, and the bacteria were spread by airflow and water droplets. High humidity (more than 90%), rising temperature on sunny days after several days of continuous rain (night temperature at 15-20 ℃) will cause disease outbreaks; disease will be aggravated if there are many diseased flowers or leaves, or Xie flowers fall on leaves; the use of water spraying method to control spider mites often aggravates the occurrence of diseases.

3. Prevention and cure method

(1) cultivation techniques for disease prevention: timely removal of diseased leaves, diseased flowers or withered flowers, if gray mold layer is produced, it must be covered with a bag and then picked; the method of spraying water to control leaf mites is absolutely not advisable; the greenhouse must be ventilated and cooled and dehumidified (below 80%) on a sunny day after continuous overcast, and drained in time after outdoor rain.

(2) Chemical control: it can be controlled by 30% water dispersible granule of pyrimidine, 20g water 15~25kg per bag with an interval of 57d, or with 18% Baozhida 20ml and water 15~30kg.

Mites

1. Symptoms and harm

There are mainly tarsal mite, cinnabar spider mite and so on, which propagate quickly and are difficult to control.

two。 Prevention and cure method

The main results are as follows: (1) cultivation techniques for disease prevention: ① cleans up withered leaves and residual branches in time to reduce the source of insects; ② planting insect-free seedlings.

(2) Chemical control: 2% avermectin 1000 times, 40% dicofol 1000 times, 20% acaric EC 1000 times 2000 times, 15% acarone EC 1500 times 2000 times, etc.

Aphids

1. Symptoms and harm

Adults and nymphs usually cluster on the back of the leaves, new leaves and young buds to suck the juice, which makes the damaged leaves lose luster and curl, and the buds are deformed and can not blossom normally, and the damaged plants grow slowly, even wither and die.

two。 Prevention and cure method

The main results are as follows: (1) the cultivation techniques should keep the cultivation place and surrounding environment clean and tidy, reduce the source of insects, plant insect-free seedlings, and trap and kill with insect traps.

(2) during the period of chemical control, insecticides were sprayed once every 5 to 7 days for 3 times in a row. There are many insecticides to kill aphids, including 10% imidacloprid wettable powder 3000 / 4000 times, 50% aphid pine EC 1000 / 1500 times, 50% aldicarb 1500 times, and so on.

Thrips

1. Symptoms and harm

The insect is small, dark brown, slender and active; it can be observed by hand on the damaged flowers; the symptoms are that the leaves become slender and hard, the edges of the leaves curl inward, and there are many small yellow and white spots or stripes on the petals.

two。 Prevention and cure method

(1) cultivation techniques to prevent diseases and eliminate the source of overwintering insects. Remove weeds, litter and other pests; blue sticky board or other trapping devices can be used.

(2) Chemical control can be controlled by the mixture of 23% octyl thiosulfate EC 1500 times plus 10% imidacloprid 1000 times or 10% imidacloprid 1000 times.

Liriomyza sinensis

1. Symptoms and harm

The adult is small, shaped like a fly, and the egg is laid under the frontal epidermis of the leaf; the egg hatches as the larva eats mesophyll cells in the mesophyll and appears white lines, which is easy to find; but its damage occurs very quickly, so attention must be paid to observation and timely prevention and control.

two。 Prevention and cure method

The main results are as follows: (1) cultivation techniques for disease prevention and removal of weeds in the field, damaged old leaves, dead branches and leaves; use yellow plastic plates coated with sticky oil to trap adults; install anti-insect nets at the vents in the greenhouse.

(2) Chemical control can be controlled alternately with 1500 times of 75% Qianke wettable powder, 1000 times of 40% omethoate EC and 2000-4000 times of 20% germicidal ester EC.

Diseases and insect pests of African chrysanthemum and their control

Diseases of Gerbera jamesonii and its control

Spot disease is a bacterial disease. It is usually spread by germs with the help of Rain Water and insects. The occurrence of spot disease requires timely removal of diseased leaves and spraying the solution of methyl topiramate wettable powder for treatment.

Mosaic disease

African chrysanthemum can also suffer from mosaic disease, which can cause the leaves of African chrysanthemum to fade green, deformed leaves, grow patches, and affect flowering or plant death. The occurrence of mosaic disease requires timely spraying.

Powdery mildew

The outbreak of powdery mildew in African chrysanthemum is mainly harmful to the leaves, showing white spots and gradually expanding. Powdery mildew of African chrysanthemum is mostly caused by germs and is easy to break out when the temperature is high and the ventilation is poor. The occurrence of powdery mildew requires timely improvement of the growth environment and spraying agents, such as 1500 times of thiophanate methyl.

Leaf spot disease

Leaf spot is also a common disease of African chrysanthemum. The occurrence of leaf spot is also caused by pathological changes on leaves. Generally speaking, the occurrence of leaf spot is caused by environmental factors, lack of light or poor drainage. If leaf spot occurs, it can be sprayed with carbendazim.

Grey mold disease

Botrytis cinerea is also caused by bacteria, the harm is greater, when the humidity is high, it is easy to occur. Humidity control is the key to prevention and treatment, which can strengthen ventilation and methyl topiramate solution is needed for prevention and treatment at the initial stage of the disease.

In addition, African chrysanthemum also has root rot, virus disease, sclerotinia disease, blight and so on. It needs to be treated according to the incidence of the disease.

Insect pests of African chrysanthemum and its control of whitefly

Bemisia Tabaci is a common pest of African chrysanthemum. It is found that pests need to clean up the growth environment of African chrysanthemum in time, select chemicals and use them correctly to avoid the lack of insecticide repellent caused by drug resistance.

Thrips

Thrips are also a common pest of African chrysanthemum, and cooking pesticides is a good way to find thrips. Dichlorvos or imidacloprid can be sprayed.

Cabbage worm

The harm of Pieris rapae is mainly divided into larvae and advanced instar larvae, which need to be sprayed and sprayed several times in time to prevent the harm from further spreading.

The control of African chrysanthemum spot disease African chrysanthemum is cultivated in protected areas for years. Due to the warm, humid environment and poor air flow, it is easy to lead to the occurrence of insect pests and diseases. Among them, one of the most common diseases is African chrysanthemum spot disease, which is caused by fungi. Small purple-brown spots appear on the symptomatic leaves, which gradually enlarge into large spots with concentric wheel patterns (2 mm to 5 mm in diameter). In the later stage, the flower center is rotten, with sparse grayish-brown dusty fungal filaments on it. In general, the lower lobe is the first to develop the disease. Excessive use of ammonia fertilizer is easy to cause disease. Soil viscous weight and poor drainage are also important conditions to induce diseases. Control methods: (1) Chloropicrin fumigation can be used in soil treatment to effectively kill pathogens and reduce bacterial accumulation from the substrate. (2) the most suitable temperature for the growth of African chrysanthemum was 20 ℃ to 25 ℃ and kept above 10 ℃ at night, which was not easy to occur disease under the condition of low temperature and low humidity. (3) Fungicides are sprayed every 7 to 10 days, such as 75% chlorothalonil, 50% carbendan and 1000 times methyl topiramate, the control effect is obvious. (Gao Shangshi)