Crabapple Variety Resources and Pest and Disease Control Cultivation Techniques

  Crabapple is the general and common name for several plants of the genus Malus and several plants of the genus Chaenomeles. The several plants of the genus Malus mainly include Malus 'Radiant', Malus 'Sparkling Sprite', Malus 'Kelsey', Malus 'Pink Roof', Malus 'Fire of the Plateau', Malus 'Adams', Malus 'Ruby', and Malus 'Winter Red Fruit'; the several plants of the genus Chaenomeles mainly include Chaenomeles speciosa, Chaenomeles speciosa 'Rugosa', Chaenomeles speciosa 'Lanata', and Chaenomeles japonica. Today we will focus on the several plants of the genus Malus, as detailed below.

  1 Identification of Crabapple Varieties

  1.1 Identification by Family and Genus

  Malus 'Radiant', Malus 'Sparkling Sprite', Malus 'Kelsey', Malus 'Pink Roof', Malus 'Fire of the Plateau', Malus 'Adams', Malus 'Ruby', Malus 'Winter Red Fruit', and others all belong to several plants of the genus Malus. The specific identification methods are as follows:

  1.2 Identification by Leaf, Flower, Branch, and Fruit

  1.2.1 Malus 'Winter Red Fruit': Deciduous shrub or small tree, plant short and small, green, margins with rounded blunt serrations; corymb inflorescence, flowers light pink, blooming in spring; fruit ellipsoid, single fruit initially green, bright red when mature, not falling through winter, and can persist until February to March of the following year before gradually falling off.

  1.2.2 Malus 'Sparkling Sprite': Flowering deciduous small tree, tree form compact, new leaves red, old leaves green; flowering period late April, flower color pink, fruit bright red, turning brilliantly red like fire by June, until deep winter; fruit ripening period June to December, fast growth, simple cultivation and management, relatively tolerant of poor soil, and with relatively strong cold resistance and saline-alkali resistance, making it an excellent landscaping tree species.

  1.2.3 Malus 'Fire of the Plateau': Deciduous small tree, tree form upright, branches and trunk dark red in winter; spring buds sprout in early March, new leaves bright wine red, mature leaves gradually turning olive green with a purple tint; flowering period early April, flower buds deep red, flowers deep pink, brightly colored.

  1.2.4 Malus 'Adams': Deciduous small tree, tree form upright, crown round and compact; flowering begins in early April, flower buds deep red, gradually turning deep magenta after swelling, open flowers light magenta, color gradually fading toward the center; June fruit light wine red, olive-shaped, an important winter fruit-viewing variety.

  1.2.5 Malus 'Ruby': Deciduous small tree, a landscaping and color-enhancing tree species whose leaves, flowers, fruits, branches, and tree form are all ornamental, all exhibiting ruby color, with the characteristics of "red leaves, red flowers, red fruits, and red branches."

  1.2.6 Malus 'Kelsey': Deciduous small tree, tree form an open round shape; flowering begins in early April, flower buds deep pink, flowers deep red after opening and gradually becoming lighter, double-petaled, abundant and dense; fruit dark purple-red, surface with a layer of blue-purple waxy bloom, maturing from late August to early September, turning yellow before falling off.

  1.2.7 Malus 'Radiant': Flowering deciduous small tree, tree form compact, bark longitudinally fissured, with many thorn-like short branches; young leaves purple-red, new leaves red, flower color pink, flowers blooming abundantly and brilliantly; flowering period late April, flowers deep pink, dazzling, with a large number of flowers.

  1.2.8 Malus 'Pink Roof': Crown cup-shaped, crown width narrow and small, tall and upright; trunk deep pink, becoming increasingly red after winter, new leaves red then turning purple-red; leaves elliptical to ovate, serrations shallow, apex acuminate.

  2 Maintenance and Management of Crabapple Tree Species

  2.1 Fertilizer and Water Management

  Crabapple likes light, is cold-tolerant and drought-tolerant, but dislikes waterlogging, so water thoroughly when watering; fertilize 1-2 times per year, mainly with organic fertilizer, generally before spring buds sprout or after leaf fall in autumn.

  2.2 Pruning

  Crabapple tree species have long and short branches; short branches are flower branches, long branches are vegetative branches. After flowering, promptly thin out overly dense branches, dead branches, and diseased and pest-infested branches; long branches can be appropriately shortened; during the growing season remove suckers at branch forks, thin out inner-canopy branches, and maintain ventilation and light penetration; in winter little pruning is needed, but appropriate thinning should be done according to tree form to keep the crown full and the flowers abundant and colorful.

  2.3 Pest and Disease Control

  2.3.1 Aphids: Aphids harm tender green branches and leaves, causing new shoots to stop growing, leaves to become distorted and curled, and also bring about sooty mold and spread viral diseases; in late autumn spray 40% omethoate 300x solution for protection; when the disease occurs, spray 20% imidacloprid emulsifiable concentrate 2000x solution or Yafeng 1:2000 solution for control, generally spraying once every 7-10 days, for 2-3 consecutive sprays.

  2.3.2 Scarab beetles: Strengthen control of underground pests, use phoxim spray to kill white grubs; during the adult damage period, spray 40% omethoate 1000x solution or 90% trichlorfon crystal 800x solution for control.

  2.3.3 Lace bugs: Use 50% malathion emulsion 400x solution, 50% fenitrothion emulsion 2000x solution for control.

  2.3.4 Red spider mites: Mainly harm old leaves and the underside of leaves; larvae, nymphs, and adults suck the sap from the underside of leaf surfaces, causing large numbers of leaves to fall off; use 20% tetradifon wettable powder 800x solution, or 50% monocrotophos emulsifiable concentrate 2000x solution for control.

  2.3.5 Brown spot disease: From after leaf fall in winter to before budding the following spring, spray once with crystal lime-sulfur mixture or Bordeaux mixture of equal amounts; after the disease occurs during the growing season, spray 70% thiophanate wettable powder 600-800x solution, or 50% carbendazim wettable powder 400-600x solution, generally spraying once every 10-15 days, for 2-3 consecutive sprays.

  2.3.6 Crabapple rust disease: Spray 0.1-0.3°Be lime-sulfur mixture or triadimefon emulsifiable concentrate for control.

Crabapple Propagation and Pest and Disease Control Cultivation Techniques

   Crabapple is a landscaping tree species with extremely high ornamental value. Its beautiful tree form allows viewing of both flowers and foliage, and it can be planted in courtyards, parks, and along roadsides. Below are the crabapple propagation and pest and disease control cultivation techniques; interested friends can refer to them.

   1 Cultivation Techniques

1.1 Land Preparation

    Choose a plot with deep soil, fertile humus, and good drainage. In autumn, deep plow 35cm. Before plowing, apply sufficient base fertilizer, applying 1500kg of decomposed farmyard manure per mu, then rake level and make ridges.

  1.2 Planting

    Purchase 1-year-old seedlings and plant at a spacing of 0.8m × 1.5m. Before planting, dig holes; after planting, surround with soil to form a water basin to help retain water and facilitate watering, and water thoroughly once immediately after planting.

1.3 Grafting

    1.3.1 Rootstock. In production, to save costs, grafting is mostly used to propagate seedlings. Use "T"-shaped budding. In Heilongjiang Province, Malus baccata is chosen as the rootstock. Select 2-year-old healthy plants free of pests and diseases as rootstock. In mid-June, cut back the rootstock, and 7-10 days before budding, cut off branches on the rootstock root portion below 10cm from the ground.

    1.3.2 Scion. Select healthy branches that are 3 years or older, have flowered, and have plump leaf buds. After selection, cut off the leaves and process immediately.

    1.3.3 Scion treatment. After cutting the scion, treat with a concentration of 50mg/L naphthaleneacetic acid, placing the base 5-10cm of the scion into the treatment solution, treating for 20-30min, then remove and set aside.

    1.3.4 Grafting. Use a budding knife to make a horizontal cut 0.3-0.8cm above the selected leaf bud, 0.5-0.9cm long, completely cutting through more than 1/3 of the scion's bark layer. On the selected rootstock, cut a "T" shape, pry open the cut on the rootstock, insert the scion with the scion's leaf petiole facing up; after insertion, align the upper end of the scion with the horizontal cut of the "T" shape, being careful not to wrap over the leaf bud and petiole. Check whether the graft has survived 5 days after grafting; after survival, remove the binding about 12 days later to avoid hindering growth of the union.

1.4 Transplanting

    Choose a plot with flat terrain, deep soil, and fertile humus; prepare the land and make ridges. Select robust 1-year-old seedlings free of pests and diseases, and transplant at a spacing of 80cm × 90cm. When transplanting, dig holes, water thoroughly after planting, and tread firm. When transplanting in dry weather, plant with water; after transplanting and seedling recovery, promptly remove new buds sprouting from the roots, then carry out routine field management.

1.5 Field Management

    1.5.1 Water regulation. After transplanted seedlings are planted, water 2-3 times before seedling recovery; after branches sprout new leaves, water as appropriate according to soil moisture; in drought, replenish water promptly, and in the rainy season drain promptly. From the second year after planting, seedlings have a certain drought resistance, so watering frequency can be reduced; water once with winter irrigation water before winter, and once with thawing water in spring.

    1.5.2 Weeding and loosening soil. During the period of vigorous plant growth, weeds grow densely and must be removed promptly; weeding should be combined with loosening the soil, and care should be taken not to damage the seedlings, especially the root system.

    1.5.3 Fertilization. When plants enter vigorous growth with lush leaves and many flowers, whether in vegetative growth or flowering period, a certain amount of fertilizer needs to be applied regularly. Apply base fertilizer before planting, applying 30kg of diammonium phosphate per mu and 1500kg of decomposed farmyard manure per mu. During the new shoot growth period, flowering period, and before leaf fall, apply 1 time each of N, P, K compound fertilizer in combination with watering, applying 30kg per mu; before the vigorous growth period, spray 0.5% potassium dihydrogen phosphate solution for foliar fertilization to promote branch and leaf growth.

1.6 Pruning

    Malus 'Royalty' is an ornamental crabapple, especially valued for its foliage. Prune before plants sprout in spring; when pruning, on the basis of shaping, retain as many branches as possible, appropriately shorten some, and do not prune heavily; cut off diseased and pest-infested branches, dead branches, drooping branches, inner-canopy branches, and crossing branches. For special landscaping seedlings, such as when cultivated as flower hedges or color blocks, the focus should be on controlling plant height and promoting more new branches and leaves.

1.7 Pest and Disease Control

   1.7.1 Diseases. Mainly black spot disease; symptoms are dark brown elliptical lesions on leaves, on which dark black mold-like fungal conidia grow, seriously affecting normal leaf photosynthesis and respiration; in severe cases, leaf color becomes lighter, causing leaves to dry up and die, seriously affecting plant growth. Control methods:

    1) Strengthen field management, promptly prune and trim, remove diseased branches and leaves, and burn them in a centralized manner. 2) In the plum rain season, promptly spray 1-2 times with 60% thiophanate-methyl wettable powder 800-1000x solution, or 55% carbendazim wettable powder 500-700x solution; spray the 2 chemicals alternately, for 2 consecutive sprays, once every 10 days.

    1.7.2 Pests. Mainly yellow stinging caterpillars, which harm plant leaves, causing weak plant growth, yellowed and withered fallen leaves, withered branches, and in severe cases plant death. Control methods:

    1) At night, use their phototaxis and use arc lamps to trap and kill them. 2) During the plant dormancy period, manually remove cocoons and burn them in a centralized manner. 3) Once pest damage occurs, promptly spray 55% fenitrothion emulsion 600-900x solution, or 35% wettable carbaryl powder 400-600x solution, or 70% trichlorfon crystal 1200-1500x solution. 4) Use their natural enemies for biological control, protecting and utilizing natural enemies such as Schreineria coccinellae and Eurytoma appendigaster.

    The above are the crabapple propagation and pest and disease control cultivation techniques. If you want to grow crabapple well, you need to strengthen field management and pest and disease control.

Pest and Disease Control of Tuberous Begonia Flower Seedlings

The main diseases of tuberous begonia include powdery mildew, leaf spot disease, gray mold, and crown rot. Powdery mildew and leaf spot disease cause relatively serious damage.

1. Powdery Mildew

(1) Symptom characteristics: Powdery mildew occurs not only on leaves but also on petioles, stems, and flowers. Lesions on leaves are nearly circular but with irregular white powdery mold spots, and the mold layer is relatively thin. Later, white powdery spots often merge with each other, covering the leaves, and appear light brown. Lesions on stems, petioles, and flowers are similar. When the disease is severe, leaves dry up and fall off early. When natural conditions are suitable, powdery mildew pathogens cause damage in cycles without needing to overwinter. Mild climate with alternating dry and wet conditions favors the occurrence of powdery mildew.

(2) Control methods: Choose varieties with both high ornamental value and disease resistance for planting. Strengthen cultivation management, plant at reasonable density, and ensure good ventilation and light penetration. In the early stage of the disease, spray 2% triadimefon emulsifiable concentrate 2500x solution or 40% Fuxing emulsifiable concentrate 6000-8000x solution, or 50% carbendazim-sulfur suspension concentrate 600x solution. Once every 10-15 days, for 1-2 control applications.

2. Leaf Spot Disease

(1) Symptom characteristics: In the early stage of the disease, lesions are blister-like, dark green, gradually turning transparent yellow; lesions expand and merge into dark brown dead spots, with white mucus (bacterial ooze) on them, forming a light gray bacterial film after drying, and later perforating and rupturing, causing the entire plant to wilt and die.

(2) Control methods: Use disease-free plants to propagate flower seedlings, and disinfect the flower soil. Planting density should be reasonable to facilitate ventilation and light penetration, and avoid splashing water onto leaves when watering. When diseased leaves are found, remove them promptly and burn them in a centralized manner. When the disease is relatively severe, promptly spray 72% agricultural streptomycin 4000x solution.

3. San Jose Scale

(1) Damage characteristics: It harms many ornamental flowers. Female adults and nymphs mostly gather on tender branches and tender leaves to suck sap, causing weak growth of branches and leaves, and in severe cases withered branches and trunks and early leaf fall.

(2) Control methods: San Jose scale is an international quarantine object; strengthen quarantine when introducing seeds, and strictly prohibit introducing seeds from epidemic areas. Flower fields should be chosen in locations with good drainage, fertile soil, and high, dry terrain. Promptly prune and trim to ensure ventilation and light penetration. When occurrence is severe, spray 50% fenitrothion 1000-1500x solution during the nymph hatching period; spraying should be uniform, and tender branches and the shaded side of leaves should be key spraying areas. Once every 10-15 days, for 2-3 consecutive sprays. Take care to protect natural enemies such as parasitic wasps to reduce damage.