Methods and Technical Key Points for Pest and Disease Control in Catalpa (Catalpa bungei)

Anthracnose Disease Control

When catalpa is infected with anthracnose, its leaves and young shoots suffer greatly, and the disease is especially likely to occur under high temperature and high humidity and poor ventilation. If infected, catalpa leaves wilt and then drop.

Therefore, for anthracnose, during prevention keep the environment well ventilated and well lit, and maintain a good supply of water and fertilizer. Doing so can improve the disease resistance of catalpa, but if infection still occurs, spray a disease-prevention preparation for control, once a week, for 3-4 consecutive sprays, and the disease can be effectively controlled.

Root-knot Nematode Disease Control

The root system of catalpa suffers from root-knot nematode disease. Generally the main root, lateral roots and small roots are all attacked. This disease produces galls on the roots of catalpa, then the root system gradually rots and eventually the plant dies.

Because this disease is quite stubborn, quarantine should be strengthened before planting to avoid introducing diseased seedlings. Once it occurs, 10% fosthiazate powder or 98% dazomet micro-powder can be applied to the roots.

The above is the introduction to pest and disease control in catalpa. Next let us look at what value catalpa has!

Cultivation and Pest and Disease Control Techniques for Catalpa

Catalpa, also known as golden-thread catalpa, is a deciduous tree of the genus Catalpa in the family Bignoniaceae. It is mainly produced in China's Yellow River basin and Yangtze River basin, and is also distributed in North China and the Zhejiang-Anhui area. The catalpa trunk is tall and straight and grows rapidly. It is suitable as a shade tree and street tree, and can also be used to accent lawns and rockeries, making it a good material for landscaping. Its cultivation and management techniques are introduced below for reference only.
   Morphological Characteristics and Ecological Habits
The catalpa can reach 35 m in height, with a tall and straight trunk and an obovate crown. The bark is gray or dark brown with shallow longitudinal fissures. Old trees have gall-like protrusions on the trunk, while young branches are grayish green and hairless. Leaves are opposite or in whorls of three, triangular-ovate or long-ovate-elliptic, with a gradually pointed tip and a truncate to broadly cuneate or heart-shaped base, 5 cm to 17 cm long, entire, with purple glandular spots on the underside. The raceme is terminal, with 3 to 12 flowers, and the corolla is light pink with purple spots inside. The capsule is 25 cm to 45 cm long and about 5 mm in diameter, and the seeds are flat with white long hairs at both ends. The flowering period is April to May, and the fruiting period is September to October.
Catalpa is light-loving, and seedlings are slightly shade-tolerant. It prefers a warm and humid climate but is not tolerant of severe cold. Catalpa is neither drought-tolerant nor waterlogging-tolerant, nor tolerant of barren soil. It prefers moist, fertile, well-aerated sandy loam and can tolerate mildly saline-alkaline soil, growing normally in mildly saline-alkaline soil with a pH of 8.8 and a salt content of 0.15%. It has strong resistance to sulfur dioxide and chlorine gas, and a strong dust-retention capacity.
   Planting Methods
When planting catalpa in landscaping, it can be done in both spring and autumn. The spring planting time is late March to mid-April, and in autumn it should be done from mid-November to early December. Before planting, dig the planting holes as required. The size of the planting hole should be no less than 1.2 m × 1.2 m, with a depth of no less than 80 cm. Topsoil and subsoil should be piled separately. If the soil quality does not meet the requirements, the soil should also be replaced. Catalpa with a diameter at breast height of less than 10 cm can be planted bare-rooted, while seedlings larger than 10 cm are best planted with a soil ball, which can maintain a relatively high survival rate. When planting catalpa, be sure not to plant too deep, as planting too deep can easily cause the plant to suffer from suppressed buds. Even for seedlings planted in autumn, the soil mound should be opened when watering in early spring of the following year, which is beneficial for the plant to sprout. Generally speaking, when planting bare-rooted seedlings, the soil can be filled 2 cm to 3 cm above the original soil mark, while seedlings with soil balls should be level with the original soil ball. Catalpa likes fertilizer, so some decomposed and fermented barnyard manure should be applied as base fertilizer at planting. The base fertilizer should be mixed evenly with the planting soil; if not mixed evenly, it can easily burn the roots.
When planting in spring, water immediately with the first watering, then water a second time after three days, and a third time after another five days. For autumn planting, the number of waterings should be determined according to the planting time. If planted in mid-November, water twice thoroughly, that is, water immediately after planting for the first watering, and water a second time after seven days; if planted in early December, one thorough watering is enough. After planting, supports should be set up promptly for larger seedlings to prevent wind or human shaking.
   Water and Fertilizer Management
Catalpa has relatively strict water requirements, which should be given attention in daily maintenance. Taking seedlings planted in spring as an example, in addition to watering the first three times well, one to two thorough waterings should also be given in each of May, June, September and October. July and August are periods of abundant rainfall, so if it is not too dry, watering can be omitted. In early December, water fully and thoroughly for freeze protection. In early March of the following year, water promptly to revive growth, and in April, May, June, September and October, give one to two thorough waterings each, and in early December water for freeze protection. In the third year, watering can follow the method for the second year. After the fourth year, in addition to watering well for reviving growth and freeze protection, the plant can rely on natural rainfall for growth, but when the weather is too dry and rainfall is low, it should still be watered. For street trees that have grown for many years, watering should also be done during drought, which is beneficial for plant growth and prolonging lifespan.
Catalpa likes fertilizer. In addition to applying sufficient base fertilizer at planting, some decomposed and fermented sesame paste residue or cow and horse manure should also be applied at the end of autumn each year together with the freeze-protection watering. In early May, some urea can be applied to the plant, which can make the branches and leaves luxuriant and accelerate growth. In late July, some phosphorus and potassium fertilizer should be applied, which can effectively increase the degree of lignification of the branches and help the plant overwinter safely.
   Shaping and Pruning
Catalpa is tolerant of pruning and has strong sprouting ability. Before planting, catalpa is generally subjected to trunk truncation, and the trunk height can be determined according to use requirements or design requirements. In spring, when the new shoots have grown to about 30 cm, among the branches closer to the top, select three or four branches that are strong, evenly distributed and not on the same trajectory as the main branches, and prune away all the other new shoots. During the growing season, the main trunk will also sprout some buds, which should all be removed promptly to prevent excessive consumption of nutrients. The new branches of catalpa grow quickly and can reach 80 cm to 120 cm in the same year. After leaf fall in late autumn, perform medium-short pruning on the selected main branches, retaining 40 cm to 60 cm, and be sure to keep outward-facing buds.
In the process of cultivation and management, some people often do not perform short pruning on the main branches and let them grow freely. The result of this is that the crown of the catalpa becomes narrow and does not open up, which is neither attractive nor provides much shade. Therefore, medium-short pruning of the main branches and retaining outward-facing buds are favorable measures for expanding the crown of catalpa. In late spring of the second year, screen the new small branches on the main branches, retaining one or two new branches on each main branch as lateral branches. The selected branches should be robust and must not cross each other, and all other branches should be removed. After leaf fall in late autumn, perform medium-short pruning on these branches again, likewise retaining outward-facing buds. After the above pruning, the basic tree shape of catalpa is formed. In subsequent maintenance, it is only necessary to remove drooping branches, crossing branches, overly dense branches, diseased and pest-infested branches, and dead and dried branches.
   Pest and Disease Control
1. Common pests: Perillus bug (perillus bug), paulownia tortoise beetle, lymantriid moth (lymantriid moth), white-kidney noctuid, frost hawkmoth, ginkgo giant silkworm moth, catalpa shoot borer, green leafhopper, etc.
If perillus bug occurs, spray 20% Confidor soluble concentrate 3000 times dilution during the adult and nymph stages to kill it; if paulownia tortoise beetle occurs, spray 3% high-permeability fenoxycarb emulsifiable concentrate 3000 times dilution during the young larval stage to kill it; if lymantriid moth occurs, spray 20% Confidor soluble concentrate 3000 times dilution during the larval stage to kill it; if white-kidney noctuid occurs, spray 48% Bacillus thuringiensis during the larval stage to kill it, and use 20% diflubenzuron suspension concentrate 7000 times dilution to kill larvae before the 3rd instar; when frost hawkmoth occurs severely, spray Bt emulsion 500 times dilution to kill it; when catalpa shoot borer occurs, spray 10% imidacloprid wettable powder 1000 times dilution for control; for green leafhopper damage, spray 25% buprofezin wettable granules 1000 times dilution or 48% chlorpyrifos emulsifiable concentrate 3500 times dilution during the nymph stage.
2. Common diseases: including catalpa anthracnose and catalpa root-knot nematode disease.
Catalpa anthracnose mainly harms catalpa leaves and young shoots, and is prone to occur during periods of high temperature and high humidity and in environments with poor ventilation. After onset, the leaves wilt and drop. During maintenance, attention should be paid to ventilation and light transmission, and water and fertilizer management should be strengthened to improve the disease resistance of the plant. If it occurs, spray 80% thiophanate-methyl wettable granules 500 times dilution for control, once every seven days, and three to four consecutive sprays can effectively control the disease.
Catalpa root-knot nematode disease mainly harms the root system of catalpa. The main root, lateral roots and small roots can all be infected. After onset, some gall-like structures grow on the root system, and then the root system rots, causing the plant to gradually die. This disease is relatively stubborn. Before planting, quarantine should be strengthened to prevent the introduction of diseased seedlings. If it occurs, 10% fosthiazate powder (3 kg to 4 kg per mu) or 98% dazomet micro-powder (5 kg to 6 kg per mu) can be applied to the roots for control.
   Propagation Methods
Catalpa can be propagated by sowing, root burial, cuttings and grafting, among which root burial and grafting are commonly used.
1. Root burial method: In late March, select root sections 1 cm to 2 cm thick and 12 cm to 20 cm long from robust catalpa trees with a diameter at breast height of more than 15 cm, and the cut should be smooth. Bury them obliquely into the soil with a plant and row spacing of 20 cm × 20 cm, with the thick end upward and the thin end downward. When burying the roots, be sure to press the soil firmly so that the roots and soil are closely combined. The upper end of the root should be slightly 2 cm below the ground. After burying, tread lightly, then water thoroughly.
The flat burial method is to place the root sections flat in a trench and then fill and tread the soil firmly, with a plant and row spacing of 30 cm × 30 cm. About 20 days after root burial, sprouts can emerge. When the seedlings are about 15 cm tall, remove tillers promptly, retaining only one robust branch per root section. In early May, apply urea once at 50 kg/mu, which can accelerate the growth of young seedlings. In mid-June, apply a phosphorus-potassium compound fertilizer once more to increase the degree of lignification of the seedlings. In the second year, transplant the young seedlings with a plant and row spacing of 60 cm × 60 cm.
2. Grafting method: For grafting catalpa, use catalpa ovata (Chinese catalpa) seedlings as rootstock. In late March, sow catalpa ovata seeds by the drill method. One month after the seedlings emerge completely, apply urea once at 50 kg per mu to accelerate the growth of the seedlings. In mid-April of the second year, use the bud grafting method for grafting. After grafting, cover the grafted bud with a plastic bag to retain moisture. After the bud survives, remove the plastic bag.

Approaches to Plant Pest and Disease Control

1. Rational use of chemical control to curb the spread of pests and diseases. Chemical control uses the toxicity of chemical agents to control pests and diseases so as to maintain the normal growth of garden flowers and trees. Many important pests and diseases can often be effectively controlled if pesticides are used promptly and reasonably. Chemical control also has the characteristic of taking effect quickly. When some pests and diseases are about to break out or have already broken out, timely chemical control can often promptly control the spread of pests and diseases. In addition, chemical control has a relatively wide range of application and is less affected by regional and seasonal factors, so it can often be used in different types of areas and in different seasons. However, long-term heavy use of pesticides also brings some adverse consequences, mainly environmental pollution, harm to natural enemies, and easy development of pesticide resistance in pests and diseases.

2. Give play tointegratedcontrol advantages and improve control effectiveness. Integrated control takes “prevention first, integrated control” as its principle, rationally applying cultivation, chemical, biological and physical methods and other effective ecological means to keep pests and diseases at the lowest level so as not to cause harm. Its advantages are:

1. Coordinate measures and reduce conflicts. If chemical control and biological control are coordinated, it is possible to kill pests and diseases while also giving greater play to the role of natural enemies. For example, using systemic insecticides by smearing stems, trunks and root irrigation can control aphids, red spiders and scale insects at an early stage. Selecting natural enemies with relatively strong resistance to pesticides and combining them with selective agents that are less harmful to natural enemies is a way to avoid or reduce conflicts.

2. Strive for simultaneous control and simplify measures. In nature, multiple pests and diseases often occur at the same time, and controlling them separately causes duplication. Taking one dominant pest or disease as the target, grasping the key stage of plant development and the favorable timing for pest and disease control, and concentrating pesticide application can also control others. According to the occurrence of pests and diseases at the time and place, seize the favorable opportunity and adopt targeted measures such as releasing natural enemies, using microbial agents and pesticides to achieve simultaneous control.purpose。

3. Make up for each other's shortcomings and complement each other. The environmental factors that constitute the occurrence of pests and diseases and the reasons affecting their occurrence are many-sided, and control measures each have their own advantages and limitations. Therefore, it is necessary to adopt measures that make up for shortcomings and improve effectiveness. For example, when controlling the underground pest “seed maggot”, emphasizing the combination of fertilization and chemical killing of adults can basically control its damage.

3. Establish a garden plant protection system and promote the development of ecological gardens. Garden plants and crops and forest trees have many common points and internal connections, but they also differ greatly. Cities are the carriers of garden pests and diseases, and cities are man-made environments, which have undergone qualitative changes compared with the natural environments of agriculture and forestry. For example, temperatures are relatively high, relative humidity decreases, and soil structure is complex; waste gas, wastewater and waste produced by cities pollute urban air, water sources and soil, and the ecological environment deteriorates; cities are large in scale and building density is high, hindering air circulation and exchange and making heat island effects likely. Such an environment will inevitably affect the distribution and growth of garden plant populations, and correspondingly will also affect the occurrence and development of pests and diseases. According to the characteristics of the urban macro-environment, use the mutually beneficial and mutually inhibiting relationships within plant communities to establish scientific and reasonable artificial plant communities so that they promote each other, restrain each other and reproduce together, forming a stable ecological environment and controlling the occurrence of disastrous pests and diseases. Establishing an ecologically sound and stable garden plant community, that is, an ecological garden system, is conducive to pest and disease control and can achieve effective control without pesticides or with less pesticide use. When pests and diseases exceed the allowable control threshold, pesticides should be used promptly for control to curb them. Ecological garden control embodies the principle of prevention as the main approach and treatment as the auxiliaryprinciple. It can not only produce huge ecological and environmental benefits, but also yield great economic benefits.

4. Establish an integrated control system to ensure effective control of garden pests and diseases. An excellent garden green space planning and design should not only fully display the aesthetic and recreational functions of the garden, but also meet the conditions required for establishing an ecologically stable plant community. The key is to avoid overly simple plant species, avoid selecting tree and grass species that are susceptible to pests and diseases and have fragile ecological functions, and create a good ecological environment needed for plant growth. Urban road greening should also adhere to the principle of multiple tree species, and each road should have different emphases in tree species selection, mainly using native tree species with strong adaptability and resistance to pests and diseases and exotic tree species that have undergone long-term cultivation and domestication and are adapted to the region. Taking the Huaibei area as an example, selecting tree species with relatively strong resistance to pests and diseases such as catalpa and ginkgo is appropriate. Maintenance and management is also an important measure to prevent the occurrence of pests and diseases. Carry out timely fertilization, pruning, irrigation and maintenance to ensure the vigorous growth of trees and seedlings. A robust plant has a stronger ability to resist pests and diseases than a weak-growing plant. For example, Pittosporum tobira growing in a place with poor ventilation and insufficient sunlight is susceptible to damage by the cottony cushion scale; the site environment has a great influence on trees. Sapindus mukorossi cultivated on park green spaces rarely suffers from scale insect damage, but when planted as a street tree on main streets, it suffers from scale insect damage. Therefore, attention should be paid to studying the site environment, improving site conditions, and creating a favorable environment that inhibits the occurrence of pests and diseases and promotes the vigorous growth of plant communities. From the planning and design of garden green spaces to the transformation of the site environment, scientific cultivation, rational use of maintenance techniques, strengthened preventive measures, and supplemented by chemical and biological measures, establishing a scientific integrated garden control system will certainly make garden pest and disease control achieve twice the result with half the effort, and should also be applied as an important measure in garden work.