Identification and Control Methods for Major Pests and Diseases of Plum Blossom

According to preliminary statistics: plum blossom has more than 170 kinds of pests and diseases, including more than 30 kinds of diseases and more than 140 kinds of insect pests.

The plum blossom, with its dignified plant form, vigorous trunk and branches, verdant leaves, lovely flowers, rich colors, and delicate fragrance, is one of the traditional famous flowers most beloved by Chinese people. In particular, its noble character of icy flesh and jade bone, braving frost and defying snow, "a myriad flowers dare to emerge amid the snow, a single tree first blooms to bring spring to the world," has for thousands of years been a symbol of the great national spirit of the Chinese people, who fear no violence, remain steadfast and unyielding, forge ahead, and advance bravely, and thus it has become one of the candidates for "national flower" with the loudest support. Whether learned scholars and refined gentlemen, or hardworking and plain workers and peasants, all have a feeling of attachment to the plum blossom, and therefore in parks and green spaces, community courtyards, street green islands, and balconies and rooftops, its graceful figure and charming presence and fragrant spirit can be found everywhere. Whether in large plum groves, or in groups of three or five, or as single specimens, or accompanied by pines and bamboos, and regardless of whether planted in the ground or in beds, or grown in pots and shaped, to make the plum plant have luxuriant branches and leaves, many flower buds and brilliant color, and rich fragrance, pest and disease control is the most indispensable step.

I. Identification and Control of Major Plum Blossom Diseases

1. Leaf curl disease

Leaf curl disease is a physiological disease. In ground-planted or potted plum blossoms, under water stress, the two sides of the leaves fold inward toward the center, and the entire plum plant appears tired and wilted; in severe cases, this causes a large number of leaves to fall. The reasons: on the one hand, due to high summer temperatures and little rain, dry soil, dry air, and excessively strong light; on the other hand, the plum tree itself has fine fibrous roots, and its ability to absorb and transport water is relatively poor; in addition, plum blossom leaves are rather thin, while at this time the plum plant evaporates water relatively quickly, so overall it is in a state of water deficit, which causes its leaves to curl, with the "Green Calyx plum" cultivar being the most severely affected. The leaf curling phenomenon begins around June, eases somewhat after rain, and the leaves can flatten slightly; when the weather is favorable and water supply is sufficient, leaf curling appears later, will not cause heavy leaf drop, and will not affect flower bud differentiation.

Control methods: Leaf curling is caused by the combined effect of the plum blossom's own special structure and physiological characteristics, as well as unfavorable climatic factors. Therefore, strengthen management so that its root system develops well and the tree grows vigorously, thereby improving its water absorption and transport capacity; after entering the high-temperature and drought season, strengthen watering at the roots, spraying water on the leaves, and sprinkling water in the environment, creating a relatively cool environment for it by increasing humidity and lowering temperature; for potted plum blossoms, especially shallow-pot plum stumps, and especially for the "Green Calyx plum" cultivar, a shed can be built for shade, with the shading degree controlled between 30%-40%, just enough to protect the curled leaves from falling due to excessive dehydration.

2. Chlorosis

Chlorosis is an iron-deficiency physiological disease that appears under alkaline soil conditions. For ground-planted or potted plum blossoms north of the Huai River, because the soil or potting mix is somewhat alkaline, or because they have been watered for a long time with somewhat alkaline water, the plum plant's root system remains in an alkaline environment for a long time, causing the nutrient fibrous roots to die, which in turn causes the leaves to lose green color and turn yellow. Alkaline chlorosis mainly appears on the leaves of newly sprouted tender branches; the leaves are rather small, and the areas between the veins lose green and become yellowish-white, rather irregularly, but the veins still appear green, and the older leaves in the middle and lower parts generally do not develop chlorosis.

Control methods: For potting soil or ground-planting garden soil, adjust its pH value to below 6.5; before using tap water to water flowers, let it stand for 3-5 days, and add a small amount of ferrous sulfate granules to it; during the growing season, apply alum fertilizer water once a month, which can prevent the occurrence of chlorosis; after relatively severe chlorosis appears on the leaves, a 0.3% ferrous sulfate solution can be used to water the roots, and a 0.2% solution can be sprayed on the leaves, once every half month, applying both watering and spraying, a two-pronged approach, which can help the tender leaves lose their yellow color and turn green. For a small number of potted plants, 1% vinegar solution or 0.5% citric acid solution may also be considered for watering the roots.