How to water flowers in different seasons and the incidence regularity of flower seedling rust

Rust is a common and serious disease of flowers and landscape greening trees, which is distributed all over the world and occurs frequently in all parts of China. There are many kinds of rust, which mainly harms nearly 100 kinds of flowers and trees, such as Rosaceae, Leguminosae, Liliaceae, Gramineae, Pinaceae, Cypress, Salicaceae and so on. After the disease, transpiration and respiration are accelerated, photosynthesis is weak, growth potential is weakened, leaves turn yellow and fall off early, or cause branch tumor, fruit deformity, etc., reduce yield and ornamental value, and even die seedlings, resulting in heavy losses.

1. Characteristics of symptoms

The diseased plant gets its name from the appearance of a large number of rusty spores. In leaves, stems and other parts, light green spots first appear, then expand into rust-brown blister spots, and after epidermis rupture, yellowish-brown powdery matter is scattered, which is a pile of summer spores; some become tangerine to black, which is a pile of winter spores; there are also honey yellow to dark brown spots or granules, which are sexual spore organs. There are many yellowish, grayish yellow to grayish brown slightly raised or prickly things, such as rust seed organs, tumors on branches, clumps and coarse bark, etc., and the fruit is deformed or cracked.

2. Pathogens and their life history

2.1 species of pathogenic bacteria

Rust is caused by rust parasites. Rust belongs to fungal phylum, basidiomycete subphylum, rust order. There are several common rust diseases infecting flowers and trees.

2.1.1 puccinia

Such as hemerocallis rust, turfgrass straw rust, leaf rust, stripe rust and crown rust, Zoysia rust, iris rust, chrysanthemum cypress rust and black rust, Aster rust, sunflower rust, geranium rust and Shu sunflower rust and so on more than 10 kinds.

2.1.2 single spore rust (uromyces)

Such as causing gladiolus rust, carnation rust and Aster single cell rust and so on.

2.1.3 Polyspore rust (phragmidium)

There is rust such as roses, roses and roses.

2.1.4 gymnosporangium

There are more than 20 kinds of rust such as Begonia, Tripterygium, Malus, Pyrus, juniper, cypress and other cypresses.

2.1.5 cronartium

There are peony, peony rust, pine tumor rust, Korean pine blister rust, Pinus sylvestris var. mongolica blister rust and so on.

2.1.6 sheath rust (coleosporium)

There are Aster rust, Pinus koraiensis needle rust, Pinus tabulaeformis needle rust and Pinus sylvestris var.mongolica pine needle rust.

2.1.7 phakospora

There are chrysanthemum brown rust and so on.

2.1.8 melampsora

There are Populus tomentosa rust, larch-poplar rust, Populus euphratica rust and so on.

2.2 Life History

2.2.1 Spore species

The simplest life history of rust is teliospore (symbol Ⅲ), and the most complex are five types of spores, namely, ○, Ⅰ, Ⅱ, teliospore and Ⅳ.

2.2.2 Life history type

Typical rust fungi have to go through five different developmental stages and produce five types of spores in order to complete the whole development process, while some rust fungi have variation and lack one or more spore types.

The long (circular) life history type produces five types of spore stage, which are called long life history type or long cycle life history type. among the long life history types, they can be divided into two types: transferred growth life history type and single host growth life history type. The host infected by the former after the germination of rust spores is different from the original host plants that produce rust spores, and their genetic relationship is distant, such as carnation rust, its ○ and I stages are parasitic on Euphorbia plants, Ⅱ and Ⅲ stages, parasitic on carnation plants. Pine peony column rust, its ○ and I caused pine blister rust on Pinus massoniana, Pinus tabulaeformis and other pine trees. The perennial hyphae of the disease could continue to produce rust spores in the second year, and its Ⅱ, Ⅲ and Ⅳ were on Paeonia lactiflora and peony. ○ and I of Puccinia spp., Ⅱ, Ⅲ and Ⅳ on Quercus of Fagaceae. The spore stages of single host growth life cycle forms were completed on the same host, such as rose rust caused by three polysporous rust, sunflower rust caused by sunflower stalk rust, broad bean and pea rust caused by broad bean single spore rust, etc.

The life history type of lack of summer spores can be divided into two types: rotation and single parasitism, which can be divided into two types: begonia, pear and apple caused by pear gum rust and Yamada gum rust, ○ and I occur in begonia, Ⅲ and Ⅳ occur in cypress, Sabina vulgaris, Sabina vulgaris and juniper, which produce tumors of different sizes on needles and twigs, called galls or winter spore horns, which absorb water and swell into orange juniper.

In addition, there are short (circular) life history type, only ○, I stage, overwintering with mycelium in the diseased part, infecting young buds such as plum blossom rust in the next spring. Only Ⅲ and Ⅳ stages, such as chrysanthemum white rust, sunflower rust and so on, all of these rust are single host parasitism.

3. Epidemic law of disease.

3.1 infection cycle

The infection cycle of rust is complicated, and there are great differences among different rust. The pathogen overwintered, some with mycelium or mycelium and summer spores in the diseased tissues such as buds, branches and leaves, and seed mother plants, the mycelium could survive for many years, some with winter spores and / or summer spores on withered branches and leaves and other diseased bodies, some could survive in the disease remnants and diseased tissues, basidiospores germinated to produce basidiospores, basidiospores infected to produce sexual spores and rust spores, and rust spores infected to produce summer spores and winter spores. Among the five kinds of spores, only rust spores, summer spores and basidiospores can infect the host, summer spores can be re-infected many times, while single-host rose rust spores and rust spores can be re-infected. Due to the lack of summer spores, rubber rust has no further infection, only one primary infection. Spores are mainly transmitted by the wind, but also by Rain Water dripping. After germination, rust spores and summer spores generally invade the host from the stomata, and the basidiospores can directly pass through the host epidermis or invade from the stomata. Generally, young buds, tender leaves and twigs are susceptible to infection. Only when there is a transgenic plant, can the infection cycle be completed and cause the disease.

Among the rust pathogens, only a few species such as safflower rust spread the disease through seeds, while most of them transmitted the disease through diseased seedlings, cuttings and scions. The spores spread widely with the airflow, and the basidiospores of pear gum rust can be transmitted to about 5 km. Some rusts spread with summer spores to different natural geographical regions, different countries, and even different continents hundreds to thousands of kilometers away, spanning dozens of latitudes.

3.2 epidemic factors of disease

3.2.1 Climatic factors

Among the various climatic factors, air temperature, air humidity and precipitation have great influence on the disease, most of which are the growth and development of rust, spore germination and disease, which is suitable for warm weather with slightly lower temperature. generally, the disease is more serious when the air temperature is between 10 and 26 ℃. Too high and low temperature will inhibit spore formation, survival, germination and infection, so rust occurs frequently in spring and autumn in China. The disease is closely related to the air humidity, and the air relative humidity is more than 80% for several consecutive days, especially the saturated humidity, which makes the disease serious. Spores can only germinate in water droplets or water film, and the disease is prevalent in rainy days, especially rainy days, dew or foggy days.

3.2.2 maintenance and management factors

Garden maintenance and management, that is, to improve microclimatic conditions, conducive to the growth of garden plants, but also enhance plant disease resistance. The disease can be reduced by planting loam flowers and trees which are deep in soil layer and rich in humus, but the disease is serious in sandy soil with heavy soil consolidation or poor soil water and fertility. Such as too dense planting, lack of sunlight, partial application of nitrogen fertilizer, overgrowth of flowers and trees, long-term stagnant water in nursery, poor plant growth, weak disease resistance, extensive management, not pruning in time, poor cleanliness and sanitation in the garden, many diseased branches and leaves, and serious disease caused by a large number of pathogens.

4. Comprehensive prevention and control

4.1 eliminate and reduce the source of bacteria

To prevent and cure the rust caused by the host, such as the landscape plant configuration of the new park, the ornamental plants should be strictly isolated from the host plants, such as begonia, apple, pear and other rust should be 5 kilometers apart from the transferred host cypress; rhododendron and spruce, hemlock, Aster, etc. can not be mixed with two-needle pine, three-needle pine and so on. If it has been mixed, it is best to get rid of the transferred parasites thoroughly, and if it is difficult to remove, the prevention and control of parasitic diseases should be strengthened. Apply medicine to prevent when the spores are about to disperse. In order to reduce the number of spores flying into the disease, the disease-borne plant species should be placed at the upwind of the disease-borne plant to reduce the disease. To control single host parasitic rust, from late autumn to early spring or plant dormancy, thoroughly clean up the latent plant remains of fallen leaves, fallen fruits and withered branches in the garden, and often remove diseased branches and leaves in the growing season, which can reduce the source of bacteria.

4.2 strengthen maintenance and management

Improve the plant growth environment, improve disease resistance, select suitable areas before the establishment of the garden, improve soil improvement, increase soil permeability, improve land fertility, organize garden irrigation and drainage system; select robust disease-free branches as cuttings, scions and other asexual reproduction materials, strictly remove bacteria; control planting density, should not be too dense; timely elimination of stagnant water; scientific fertilization, more rotten organic fertilizer and phosphorus and potassium fertilizer, not partial application of nitrogen fertilizer Regular pruning to remove disease and insect pests and weak branches to make the garden well ventilated and transparent; facility cultivation should strengthen ventilation and reduce the humidity in the greenhouse.

4.3 Chemical control

4.3.1 Winter application

At the end of autumn to before the sprouting of the following year, after cleaning the diseased branches in the countryside, the medicine can be sprayed with 2x 5 degree stone sulfur mixture, or 45% crystalline stone sulfur mixture 100g 150 times, or pentachlorophenol sodium 200ml 300 times, or pentachlorophenol sodium plus stone sulfur mixture mixture. When configuring, dilute pentachlorophenol sodium with 2000,300 times water, then slowly pour into stone sulfur mixture, pour fully while stirring, adjust to Baume 2o3 degrees medicine solution. Pentachlorophenol sodium powder can not be diluted without adding water into the stone-sulfur mixture to avoid precipitation. In order to control the rust on the transferred parasitic cypress, the rust should be sprayed twice in the first and middle of March in early spring to kill the overwintering spores.

4.3.2 Pesticide application in growing season

In the early stage of flower and tree disease, spray Baume 0.2-0.3 degree stone-sulfur mixture, 45% crystalline stone-sulfur mixture 300% 500 times, or 70% mancozeb wettable powder 500 times, or 62.25% Xiansheng 600 times, or 500 times 80% Dasheng Mrel 45, or 70% methyl topiramate 1000 times, or 25% triadimefon 1500 times. The newer agents to control rust include 12.5% uniconazole 3000 × 5000 times, or 43% Haolicol 4000 times, 25% Fulicu 1000 times, 25% Fulicu 1000 times, 25% o-amide 1000 times, 30% Ami Miao 3000 times, 50% Cuibei 3000 times, 10% high 3000 times, 25% Fuxing 5000 times, 50% Fuling 5000 times, 50% Leinengling 1000 times.

4.4 strict quarantine

The branch rust of many trees is quarantined. Seedlings should be introduced from disease-free areas and asexual propagation materials such as cuttings should be collected from disease-free mother plants.

4.5 breeding of disease-resistant varieties

There were significant differences in rust resistance between flower species and varieties. Therefore, the breeding of rust-resistant flower and plant varieties is an economical and effective way to control rust.