Efficient Cultivation Techniques for Heath (Erica) and Control of Major Pests and Diseases
Recently, many flower growers have asked our editor how to grow heath (Erica). There are about seven hundred species of heath worldwide, most of which originate from South Africa, earning it the title "Queen of South African Endemics." Below, we introduce a set of cultivation techniques for the propagation of 'Senhua' heath and the control of pests and diseases.
1 Cutting Orchard
1.1 Nursery Site
Choose loose, fertile, acidic to slightly acidic soil; calcareous soil may also be used. For clay soil and soil with insufficient fertility, base fertilizer must be applied in advance for soil improvement: apply 3000 kg of decomposed organic fertilizer and 50 kg of phosphate fertilizer per mu, and plow the soil to a depth of more than 25 cm, turning the base fertilizer into the soil. After plowing and harrowing fine, level the bed surface and then open furrows to make seedling beds. The cutting orchard beds are 110 cm wide, with paths 40 cm wide and more than 25 cm deep, with all furrows interconnected for smooth drainage.
1.2 Transplanting
When transplanting container seedlings, except during the high-temperature and drought season of July to August, transplanting can be done at any other time. Transplant at a plant spacing of 35 cm and row spacing of 35 cm, planting 3 plants laterally, 3500 plants per mu. After container seedlings are transported to the field edge, they must not be stacked; they should be arranged neatly on the mud ground and immediately sprayed with water to moisten. Transplant promptly, digging holes at fixed points according to plant and row spacing, with the transplanting depth slightly deeper than the original root zone of the plant, then cover the base of the seedling with fine soil and press gently.
1.3 Water
On the day of transplanting, water thoroughly to settle the roots. If there are consecutive sunny days, water once daily after transplanting to keep the soil moist. 'Senhua' heath dislikes waterlogging; if it rains, drainage should be carried out promptly.
1.4 Light
In the year of transplanting, from June to August, shade nets with 50% light transmittance should be erected to prevent sunscald and withering. From the second year onward, full-light management can be implemented.
1.5 Nutrients
Starting 15 days after transplanting, from April, apply urea once every 10 days or so at 10 kg per mu. From May to September, apply compound fertilizer once every 20 days or so at 20 kg per mu, along with phosphate and potassium fertilizers at 25 kg per mu. After October, apply decomposed organic fertilizer once at 2000 kg per mu and phosphate fertilizer at 50 kg per mu, burying them in shallow furrows between the plants.
1.6 Soil Management
In conjunction with fertilization, loosen the soil and remove weeds, achieving "remove early, remove small, remove completely," so that the seedling beds are essentially free of weeds. After rain on sunny days, loosen the soil and remove weeds promptly to prevent surface crusting.
1.7 Disease Control
Common diseases include leaf blight and anthracnose. Leaf blight damages leaves and branches, turning them yellow-brown and causing the whole plant to die. Control methods: strengthen management, apply more decomposed organic fertilizer, enhance tree vigor and improve disease resistance; remove diseased branches and leaves and burn them in a centralized manner; at the early stage of the disease, spray 50% Shibaike 500x solution or 75% chlorothalonil 500x solution or 80% zineb 600x solution, once a week, for 2 to 3 consecutive sprays. Anthracnose damages leaves and tender shoots, causing them to wither and turn brown, leading to defoliation and death. Control methods: control density, maintain indoor ventilation and light penetration; promptly remove diseased leaves and branches and burn them in a centralized manner; at the early stage of the disease, control water volume, enhance growth vigor and reduce the severity of the disease; at the early stage of the disease, spray Juxiu 1000x solution, once a week, for 2 to 3 consecutive times.
2 Cutting Propagation
2.1 Cutting Collection and Fresh-keeping
Cut current-year semi-lignified branches as cuttings, while keeping the mother plant's crown shape neat. The key to cutting collection is keeping the cuttings fresh; this should be done in the morning or evening, and the cut branches should be covered with moistened non-woven fabric and sprinkled with water to retain moisture. During transport, keep them cool and moist; after arriving at the destination, spread them out and sprinkle water as soon as possible, place them indoors and cut the cuttings promptly for insertion. Cutting should be done in early October, once a year. The height of the mother plant retained must consider not only the shaping of the mother plant into a commercial seedling but also the quantity and quality of cuttings; therefore, when only cutting branches, the original neat crown height should be retained. Cutting length is 2.5 cm, retaining 6 scales.
2.2 Plug Trays and Substrate
Use 128-cell plug trays, 54 cm long, 27 cm wide and 4.5 cm deep. The substrate formula is BM4 Count peat : perlite at 6:4.
2.3 Seedling Bed and Disinfection
The cutting seedling bed is 100 cm wide, with 3 plug trays placed lengthwise, paths 40 cm wide and 25 cm deep; the bed surface is covered with ground cloth and filled with 3 cm of sawdust, disinfected with potassium permanganate 500x solution and covered with plastic film for 24 hours. After cutting is completed, spray carbendazim 1000x solution once for disinfection.
2.4 Rooting Agent and Cutting
Use "Sensheng No. 1" plant rooting agent; dissolve every 1 g in 50 ml of alcohol for half an hour, then add clean water to a total volume of 1500 ml, stir evenly and it is ready for use; soak the cuttings for 2 seconds. Insert 1 cutting per cell, at a depth of 1 cm.
2.5 Moisture Retention and Disinfection
After filling the plug trays with substrate, water thoroughly 1 day in advance. On the day of cutting, after each seedling bed is finished, water thoroughly immediately; after the water on the leaf surface evaporates, immediately spray carbendazim 600x solution for disinfection and disease prevention, then build a small arched frame, cover with plastic film, and seal all around to maintain relative air humidity inside the frame above 95%.
2.6 Daily Management
Shade nets should be erected above the seedling bed: 1 layer in May to June, 2 layers in July to August. When the daily temperature is below 30°C, the shade nets can be fully removed for full-light management. When the air temperature inside the small arched frame reaches 37°C, spray cooling measures should be taken; especially on sunny hot days, from 10 a.m. to 4 p.m., spray once every half hour to bring the temperature below 37°C.
Check substrate moisture once daily, and water once every 3 to 4 days in the evening or early morning. On the day of cutting, while watering and spraying pesticide, also spray foliar fertilizer, either with Lufenwei powder 1000x solution or with 0.2% urea solution. About 25 days after cutting, when more than 85% of the cuttings have rooted, hardening off can begin: in the evening, remove the film at both ends for ventilation for two days, then remove all the film, and cover the bamboo frame of the small arched frame with 1 layer of shade net; after two days, remove all the shade net. After hardening off, the seedling bed is managed under full light, watering promptly and spraying liquid fertilizer, and spraying carbendazim 500x solution to prevent diseases. From hardening off to finished seedlings, the plug seedlings reach 5 cm in height; the seedling management period is 5 months, with a finished product rate of 85%.
The above is the heath cultivation method and pest and disease management compiled by the editor of Huinong Network for flower growers today. Flower growers in need can refer to it, and please introduce Huinong Network to more friends.
Occurrence of Camellia Gray Blight and Its Integrated Control Methods
Occurrence of Camellia Gray Blight and Its Integrated Control Methods
Li Gensheng, Liang Jianyi, You Guobiao, Liu Jingsheng, Lu Yeyin
(Foshan Agricultural and Forestry Technology Extension Center, Foshan, Guangdong, 528000)
Camellia has many flowers, a long flowering period, and delicate and gorgeous flower shapes, with dark green leaves that do not fall all year round, making it a flower variety deeply loved by people. Camellia is one of China's ten traditional famous flowers and is widely planted in many provinces across the country. At the same time, the camellia flowering period coincides with the Spring Festival, so it is also a high-value Lunar New Year flower. Grafting camellia onto oil tea can quickly produce tall, well-formed camellia plants; therefore, camellia has also become a very important horticultural variety for beautifying the environment. Because camellia cultivation is highly profitable, the planting area has been expanding year by year. Camellia commonly suffers from various diseases, among which gray blight caused by Pestalotiopsis is very common, often causing leaves and shoots to dry up; in mild cases it affects the ornamental value of the plant, and in severe cases it leads to the weakening and death of the entire plant. Therefore, this disease has become an important technical obstacle to the current development of camellia production.
Since 1997, we have conducted investigations and research on the occurrence and control of camellia gray blight, focusing on several flower farms in Nanhai District and the camellia production base of the Foshan Forestry Science Institute, and implemented integrated control techniques for camellia gray blight, achieving very good control results. The incidence of shoot disease in camellia gray blight dropped from the original 90—100% to below 1%.
1. Symptoms and Pathogen of Camellia Gray Blight
Occurs on leaf margins or leaf tips, appearing as circular or irregular spots. The spots are initially brown, later the center turns white, the edge is dark brown and clearly raised; on them are scattered or in inconspicuous concentric ring arrangement dark black small dots. When camellia new shoots are infected, they form light brown, elongated, clearly edged canker spots that gradually sink, shrink and crack longitudinally. The pathogen of camellia gray blight is Pestalotiopsis guepinii Desm. The acervuli are initially embedded, later exposed, disc-shaped or cushion-shaped, black; conidiophores have 1-2 annellations; the middle cells of conidia are olive-colored, the cells at both ends are colorless, and the appendages at the top of the spore number 2-5, mostly 3, unbranched.
2. Host Range, Transmission Routes and Occurrence Dynamics of the Pathogen of Camellia Gray Blight
According to relevant reports, Pestalotiopsis guepinii can grow on many plants such as Camellia, Laurus, Magnolia, Rhododendron, heath (Erica), and pine. We have successively investigated and sampled at several flower farms in Nanhai and Shunde, and found Pestalotiopsis on quite a few flowers and trees. Besides camellia, the more common ones are: Podocarpus macrophyllus, Pinus thunbergii, Chrysalidocarpus lutescens, Caryota ochlandra, ginkgo, rhododendron, nandina, cycad, mango, etc. Because Pestalotiopsis has a wide host range, it tends to easily cause mutual infection among mixed plantings of flowers and seedlings. The flower and seedling production and propagation farms in our city generally practice mixed planting of multiple varieties, and several infected flower varieties can be found in the same flower farm, such as the most common Chrysalidocarpus lutescens and Podocarpus macrophyllus, providing conditions for the repeated transmission of this pathogen.
Camellia Pestalotiopsis overwinters as mycelium or acervuli in diseased tissues, produces spores the following spring, and spreads and causes damage via wind and rain. The main period of disease occurrence is from March to November, with peaks in early to mid-June and late August to early September, closely related to the sprouting of new shoots and high-temperature, high-humidity weather. The initial onset period is around early March, when new shoots begin to be infected; by late May, as temperatures rise and rainy, humid weather occurs, the disease gradually worsens, and this is also the stage when new shoots begin to sprout. If control is not timely, the general incidence of diseased shoots in early to mid-June is 25—45%, with severe cases reaching 40—70%; by early to mid-September, the incidence of new shoot disease is 35—70%, with severe cases reaching 70—100%. Summer typhoon rain often accelerates the occurrence and epidemic of the disease.
According to investigation and observation, at some flower farms, camellia flower buds and tender leaves are also attacked by nematodes, aphids, etc., and the damage caused by nematodes, aphids, etc. creates a large number of wounds; therefore, these pests and pathogens are also one of the reasons that induce gray blight and further expand and spread the damage.
In addition, many flower farms use long-contaminated ditch water when watering flowers and even when applying pesticides, leading to re-infection by the gray blight pathogen; the control effect is unsatisfactory and the disease is difficult to control. Water source contamination has become an important hidden danger for the occurrence and spread of gray blight and other diseases.
3. Integrated Control Methods for Camellia Gray Blight
3.1 Earnestly implement various agricultural control measures
3.1.1 Strengthen cultivation management and improve the plant's stress resistance.
Apply organic fertilizer made from fully fermented and decomposed peanut bran, etc., and reasonably increase phosphate and potassium fertilizers. Carry out field irrigation and drainage work promptly to reduce field humidity as much as possible.
3.1.2 Emphasize the use of clean water sources, and do not reuse contaminated ditch water or industrial wastewater.
Water source contamination often causes repeated infection and damage by pathogens and affects the disease resistance of camellia. Where conditions permit, clean well water, spring water, river water or tap water should be used, avoiding repeated use of ditch water within the flower farm. If water sources are scarce, attention should also be paid to frequently draining, irrigating and disinfecting the ditch water to reduce its contamination level. After adopting this measure, the occurrence of camellia, Podocarpus macrophyllus, Chrysalidocarpus lutescens and other diseases that were once severely infected by Pestalotiopsis at the Nanhai Lingnan Flower Farm all decreased significantly. The incidence of diseased shoots dropped from the original 30—60% to below 8%.
3.1.3 Closely monitor and control pathogen transmission among different hosts.
Rationally arrange the planting of different varieties of flowers and seedlings that are susceptible to infection by Pestalotiopsis. For example, Chrysalidocarpus lutescens and Podocarpus macrophyllus, which are often infected and damaged by Pestalotiopsis, should have their planting areas reasonably arranged and kept at a certain distance from camellia planting areas; at the same time, various control measures should also be carried out well to reduce the degree of damage, try to avoid mutual infection and transmission of pathogens among different flower and seedling varieties, and improve the control effect.
3.1.4 Promptly remove residual branches and fallen leaves and burn them in a centralized manner to reduce pest and disease sources in the garden.
3.1.5 Earnestly manage camellia seedlings. Select healthy plants for taking scions, and thoroughly disinfect both rootstock and scion to avoid the spread of disease sources.
3.2 Chemical control methods for camellia gray blight
3.2.1 Key application period
According to observation, the main damage peak of camellia gray blight occurs in the early stage of new shoot sprouting in camellia; therefore, pesticide application for control should focus on the growth stage of new shoots (especially summer new shoots). During this stage, the application amount should be appropriately increased and the application interval appropriately shortened in order to strengthen the protection of new shoots. At other growth stages of camellia, pesticide application can be arranged as appropriate according to the severity of gray blight occurrence and the temperature and humidity conditions of the weather.
3.2.2 Application methods
The use of chemical pesticides should emphasize selecting the right pesticide for the disease, alternating pesticides and reasonable mixing. Pesticide selection: 70% thiophanate-methyl, 75% chlorothalonil, 70% mancozeb, 50% carbendazim, Shigao, copper oxychloride, Dexon, Miebingwei, etc. The above pesticides should be appropriately combined and mixed and used in rotation. For example, 7% thiophanate-methyl 800x + Miebingwei 500x, Dexon 800x + 70% mancozeb 600x, 75% chlorothalonil 600x + 50% carbendazim 600x and other formulas should be sprayed alternately. The efficacy of mixed application is significantly higher than single use.
Apply pesticides at the right time, focusing on protecting shoots during the summer new shoot growth period. Appropriately adjust the application interval: during the peak disease period, apply once every 5 d; at other times, apply once every 7—10 d. Apply pesticides for protection before typhoon rain, and carry out remedial pesticide application after typhoon rain. During the plum rain season, seize sunny periods to apply pesticides.
3.2.3 Simultaneous control of other pests and diseases
Besides camellia gray blight, the pests and diseases harming camellia also include anthracnose, brown spot, gray mold, sooty mold, nematode disease, aphids, leafhoppers, scale insects, etc. Some pests and diseases, such as nematodes and aphids, not only directly harm camellia but also indirectly aggravate the occurrence of gray blight. Therefore, while controlling gray blight, attention should be paid to simultaneously controlling other pests and diseases. For example, add systemic insecticides: quinalphos and omethoate to control nematodes and scale insects; use imidacloprid to control aphids and leafhoppers; use procymidone to control gray mold, etc.