Methods for preventing and controlling flower diseases and pests in greenhouses in spring

In spring, the occurrence of diseases and pests increases for flowers in greenhouses. In spring, this great time for flower growth, if diseases and pests occur, the economic losses are very large. How should flowers in greenhouses be protected from diseases and pests in spring?

Greenhouse flowers

Strengthening the prevention of diseases and pests in greenhouse flowers in spring is a very important part of the flower production year. For flowers in greenhouses, the disease and pest sources accumulated over a year occur and develop in this season. Therefore, the prevention of diseases and pests in greenhouse flowers in spring is mainly based on eliminating the sources of diseases and pests while promptly preventing their occurrence and development. The insect pests of greenhouse flowers in spring are mainly piercing-sucking pests such as aphids, red spiders, thrips, and mealybugs, followed by chewing pests such as cabbage white butterflies and cotton leafworms; the diseases are mainly powdery mildew, downy mildew, gray mold, damping-off, and viral diseases, followed by leaf spot disease, blight, and others.

The main steps for integrated prevention of diseases and pests in greenhouse flowers in spring are:

1. Promptly remove field weeds, dead branches and fallen leaves, and dense branches and old stubble, and destroy them in a concentrated manner.

2. Select the right pesticide, determine the concentration to use, and spray the cleaned plants and plots to kill the sources of diseases and pests.

3. Pay attention to field observation and spray pesticides in time for prevention.

4. Regulate the temperature and humidity inside the greenhouse to establish an environment unfavorable for the occurrence of diseases and pests.

5. Use fumigant insecticides and fungicides inside the greenhouse to achieve early treatment and early prevention.

6. Repel and trap pests.

Methods for preventing and controlling flower diseases and pests

Methods for preventing and controlling flower diseases and pests

For the prevention and control of flower diseases and pests in protected cultivation, the principle of "prevention first, integrated control" should be implemented, with horticultural control as the foundation, artificial control strengthened, the controlling role of natural enemies fully utilized, and chemical control combined to carry out integrated management of diseases and pests.

There are mainly three aspects to the approach of prevention first: (1) Eliminate the sources of diseases and pests or lower the base number of disease and pest occurrence. For example, plant quarantine is an effective measure adopted to prevent dangerous diseases and pests from spreading along with seeds and seedlings. Lowering the base number of disease and pest occurrence refers to reducing the number of overwintering pathogens and pests; (2) Worsen the environmental conditions for the occurrence and damage of diseases and pests, that is, create or fully utilize conditions unfavorable to diseases and pests, and change or eliminate conditions favorable to diseases and pests; (3) Promptly take effective measures to eliminate diseases and pests before they occur in large numbers and cause significant damage. For example, rationally use pesticides and adopt effective artificial and physical measures.

Integrated control is based on agricultural technical control, adapting measures to local and seasonal conditions, rationally applying chemical control, biological control, physical and mechanical control, and other measures, fully giving play to the positive role of various control methods, and organically combining and coordinating them,

making up for each other's shortcomings, so as to achieve the goal of economically, simply, safely, and effectively controlling and eliminating diseases and pests.

Take effective measures to protect flowers from invasion by pathogens and pests and to control the number of pathogens and pests; improve environmental conditions so that they are favorable to the growth and development of flowers and unfavorable to the survival and infection of pathogens and pests, thereby improving the disease and pest resistance of flowers. The specific control methods are as follows:

I. Plant quarantine

The frequent exchange and transportation of flower species and varieties between countries or regions has allowed some diseases and pests to spread and cause great losses to flower production. The South American leafminer and the American leafminer, now commonly occurring in our country, were introduced into China from abroad in 1994 due to lax quarantine, causing great losses to flower and vegetable production in our country. Therefore, blind introduction and transfer of seeds should be avoided, and quarantine regulations should be strictly implemented.

Plant quarantine includes three aspects: diseases, pests, and weeds. It is a series of regulatory measures adopted by the state to protect agricultural production from the invasion of foreign dangerous diseases, pests, and weeds. According to legal provisions, for the categories of plant products subject to quarantine and the lists of diseases, pests, and weeds prohibited from being brought in or taken out, if quarantine objects are found, they may not be imported or exported, or may be exported or imported only after disinfection treatment has eliminated the quarantine objects, so as to prevent spread and disaster. Plant quarantine is an important part of disease and pest control. Especially in the contemporary era when transportation tools are highly developed and exchanges with foreign countries are continuously expanding, strengthening quarantine work is particularly important. At the same time, the transportation of seeds, seedlings, and other cultivation materials between different regions within the country must also implement quarantine, and quarantine objects are strictly prohibited from entering new areas.

II. Horticultural control methods

Agricultural technical control methods use a series of cultivation and management technical measures in the flower cultivation process to purposefully change certain environmental conditions so that they are unfavorable to the occurrence and development of diseases and pests and favorable to the growth and development of flowers, thereby avoiding or reducing the occurrence of diseases and pests and achieving the goal of improving flower quality. Since most agricultural measures themselves are a means of high flower yield and do not require additional manpower and material resources for disease and pest control, they often achieve multiple benefits at once, meet economic requirements, and at the same time agricultural control has no adverse side effects such as polluting the environment or killing natural enemies. The specific measures of agricultural technical control methods are:

1.    Rational fertilization and scientific watering. The organic fertilizer applied should be fully decomposed. Before application, the pathogens and

pests in it should be thoroughly killed, and pests should be prevented from laying eggs on the organic fertilizer after application. When applying inorganic fertilizer, the ratio of nitrogen, phosphorus, and potassium should be reasonable. Do not apply nitrogen fertilizer in a one-sided way. Instead, appropriately increase the application of phosphorus fertilizer and potassium fertilizer, and advocate formula fertilization. The watering method should be appropriate. Avoid sprinkler watering. It is best to use furrow irrigation or watering along the edge of the pot. Watering should be appropriate. Choose to water in the morning on sunny days, and after watering, ventilate promptly to remove moisture.

2.    Keep greenhouses and conservatories clean and sanitary

Promptly remove flower branches and leaves with diseases and pests, pull out diseased plants, clear away dead branches and fallen leaves, and thoroughly eradicate weeds inside and outside the conservatory to reduce sources of diseases and pests. Diseased remnants should be buried deeply or burned.

3. Improve environmental conditions

Ventilate and exchange air frequently to reduce humidity, so as to reduce the occurrence of high-humidity diseases such as gray mold on flowers. The planting density and the placement density of flower pots should be appropriate to facilitate ventilation and light transmission between plants and reduce damage from pests such as mites. Control the temperature well; do not let it alternate between cold and hot. In winter and spring, special attention should be paid to keeping warm, while in hot summer, shade nets should be used for covering. Adjust light intensity according to the needs of flower growth. Ventilation and cooling can control the development of many diseases; while high-temperature greenhouse sealing can control the occurrence of low-temperature diseases such as downy mildew.

4. Winter plowing and deep turning

Winter plowing and deep turning for flowers cultivated in the open field has a significant effect on eliminating pests in vast areas of our country, especially in cold regions. Winter plowing and deep turning can expose most of the
larvae, pupae, eggs, and others lurking in the soil to the surface to be frozen to death or pecked by beneficial birds, and manual capture can also be carried out. Deep plowing can bury pathogens and stubble in the shallow soil into deeper soil layers, causing them to lose vitality, and can also turn pathogens originally in deeper soil layers to the surface, increasing death due to the influence of other natural factors such as light, temperature, and humidity.

5. Handle damaged plants

For annual and biennial herbaceous flowers, the residual plants after flowering and damaged plants should be immediately pulled out and burned or buried deeply in the soil; for perennial and woody flowers, after withering or leaf fall in late autumn, dead branches and fallen leaves should be promptly removed and destroyed in a concentrated manner. This measure can also reduce the number of some pathogens and pests.

6.    Timely weeding

Overgrown weeds not only compete with flowers for nutrients, affect ventilation and light transmission, and cause poor plant growth, but weeds are also a place for the reproduction of some pathogens and pests. Some viral diseases and pests often use weeds as hosts. Weeds are also a place where some diseases and pests overwinter. Therefore, timely removal of weeds is of great significance in disease and pest control.

7.    Timely pruning

In combination with flower and tree pruning, cut off diseased buds, diseased branches, diseased roots, and so on to reduce the number of pathogens, and at the same time also eliminate eggs, larvae, and adults that overwinter and oversummer on branches, reducing pest sources.

8.    Adjust the sowing period

The occurrence of many kinds of diseases and pests has a certain disease period and pest occurrence period due to the influence of temperature, humidity, and other environmental conditions, and is most serious in a certain period. If sowing is advanced or delayed, the disease period and occurrence period can be avoided, reducing damage. For example, aster seedlings are most susceptible to damage by squash beetles in the seedling stage. If sowing can be advanced, the degree of damage can be reduced. Adjusting the sowing or transplanting period has a certain control effect on pests that occur once a year, have a single feeding habit, and occur uniformly.

9.    Rational crop rotation

Avoid continuous cropping with mutually infecting flowers as much as possible, so that pathogens and pests in the soil cannot obtain suitable hosts, thereby reducing the number of pathogens and pests.

10.    Scientifically carry out the harvest and post-harvest management of bulbs and other organs. During the digging process, reduce wounds as much as possible. After digging out, promptly remove diseased

bulbs, and only after sufficient drying can they be put into storage. Wounds caused during digging easily lead to the invasion of various molds. Excessive temperature, excessive humidity, and poor ventilation at the storage site are important causes of rot in bulbs. Therefore, care should be taken during digging to minimize wounds. The storage cellar should be kept clean and sanitary. After being put into the cellar, the cellar temperature should be controlled at about 5°C, and the relative humidity should be controlled below 70%.

11.    Pay attention to the rational arrangement of flower species

According to the characteristics of flower species and the conditions of the site, arrange them rationally so that the cultivated flowers are distributed in an orderly manner, with appropriate density, obtain the space and sunlight they should have, and are in an environment with smooth air flow, thereby favoring the growth and development of flowers and disfavoring the occurrence of pathogens and pests.

12.    Select healthy propagation materials free of diseases and pests

Viral diseases of flowers occur commonly, and many propagation materials carry viruses. Therefore, virus-free tissue-cultured seedlings should be used in production. It is best to establish disease-free seed fields and collect seeds or obtain propagation materials from healthy mother plants.

13.    Select and cultivate disease- and pest-resistant varieties

Breeding disease- and pest-resistant flower varieties and cultivating flowers with strong disease resistance can protect flowers from disease and pest damage or reduce the degree of damage. This is one of the important methods for effectively controlling flower diseases and pests.

III. Biological control methods

Biological control is the use of natural enemies to control diseases and pests. Natural enemies are organisms that feed on pests or pathogens. Under natural conditions, natural enemies are widely present and control the damage of diseases and pests, especially pests. In flower care, the role of natural enemies should be consciously strengthened, such as leaving pruned pest-carrying branches for a few days before burning them, in order to protect parasitic natural enemies inside the pests.

IV. Physical and mechanical control methods

1.    Heat treatment of propagation materials

Soaking seeds or other propagation materials in water at a certain temperature can kill pathogens and pests on the surface and inside, but the temperature and treatment time must be well controlled. Excessive temperature and excessively long treatment time will affect the vitality of seeds and other propagation materials.

2.    Soil heat treatment

If conditions permit, soil can be treated with hot steam to kill pathogens, nematodes, and pests in the soil. Soil heat treatment should be carried out before planting, and the heated soil should reach a certain depth, with the soil temperature at a depth of 20 cm reaching 75°C as suitable.

3.    Mechanical barriers

Covering with agricultural film can play a certain mechanical barrier role against the introduction and spread of pathogens and pests, and can also inhibit the formation of spores of gray mold and sclerotinia.

4.    Trap and kill insects and nematodes

Use the tropisms of insects and nematodes to control pests and nematodes. For example, use yellow boards to trap and kill adult whiteflies, use fly-catching paper to trap and kill adult leafminers, and plant trap plants to trap nematodes, thereby reducing their damage to flowers.

V. Chemical control methods

Chemical control is pesticide control. It has the advantages of good control effect, quick results, and simple methods of use. But at the same time, it can also pollute the environment, cause pesticide damage, and after long-term use, pathogens and pests will develop resistance. Chemical control is an important part of integrated disease and pest control, but attention must be paid to the scientific use of pesticides.

1.    Correctly select the type of pesticide

Understand the functions of pesticides and the targets to be protected, and apply the right medicine according to the type of disease and pest. For example, the fungicide metalaxyl has a very good control effect on downy mildew of various flowers, but it cannot control powdery mildew. The insecticide pirimicarb has a relatively good control effect on the vast majority of aphids, but is almost ineffective against cotton aphids.

2.    Rationally select pesticide formulations

High humidity favors the occurrence of gray mold. Therefore, selecting procymidone smoke agents or dust formulations has a better control effect on this disease. To control scale insects, systemic granular formulations can be applied underground and systemic liquid medicine can be poured to achieve the purpose of controlling aboveground pests by applying medicine underground.

3.    Apply pesticides at the right time

It is necessary to fully understand the occurrence patterns of diseases and pests, identify weak links, and apply pesticides in time. For example, before sowing or transplanting flowers, pesticides can be applied to disinfect seedling rooms and greenhouses, treat soil and dress seeds with pesticides, and use disinfectants such as formalin to disinfect agricultural operation tools and containers such as flower pots. Eliminating diseases and pests outside the flower garden and before damage is the best strategy. For example, eliminating pathogens and pests on overwintering hosts or during the overwintering stage are both proactive approaches. For diseases, the favorable time for control is before the pathogen is infected, or before the next spore reproduction and spread, eliminating the pathogen in the initial stage of occurrence. Applying pesticide too early, the pesticide's power will decompose under sunlight and rain and fail to play its proper role; applying pesticide too late, the pathogen has already invaded, and it becomes "a belated action." For pest control, consideration should be given to the drug resistance of different pests or different developmental stages of the same pest. For example, generally for pest larvae, the 3rd instar is the dividing line. Before the 3rd instar, drug resistance is poor; after the 3rd instar, drug resistance increases significantly, and newly hatched larvae have the lowest drug resistance. Generally speaking, the resistance of Lepidoptera insects to pesticides is egg > pupa > larva > adult. Therefore, the favorable period for controlling larvae is generally before the 3rd instar, and controlling adults is even more favorable. However, controlling boring pests is different, and generally it should be at the peak oviposition period.

4.    Alternation and mixed use of pesticides

Long-term single use of the same pesticide in the same area to control diseases and pests may produce resistance within pathogen and pest populations. Therefore, rational alternation or mixed use of different types of pesticides is advocated to avoid the emergence of resistance.

5.    Safe use of pesticides and avoidance of pesticide damage

Some flowers or certain growth stages of them may be sensitive to a certain pesticide or certain pesticides. In such cases, the pesticide should be used with caution. Even if not sensitive, the pesticide concentration and dosage must be strictly controlled. Do not arbitrarily increase the concentration and dosage to prevent pesticide damage. If the pesticide used is a new drug, a test of the pesticide concentration and dosage should first be conducted on a small area, and only after it is confirmed safe can it be used on a larger area. In addition, highly toxic pesticides should be used with caution, and high-residue pesticides that seriously pollute the environment and water sources should be restricted or prohibited.

(1) Inappropriate pesticide application amount.

Excessively high pesticide concentration often causes pesticide damage to flowers, and this is the most likely problem to occur. To prevent pesticide damage, the concentration of the liquid medicine must be appropriate. Different pesticides used in different seasons for different diseases and pests and different types of flowers all use different concentrations, and preparation must be carried out strictly according to the concentrations specified in relevant pesticide manuals.

(2)    Different types and varieties of flowers, or flowers of the same variety at different developmental stages, react differently to pesticides.

For example, Bordeaux mixture and other copper-containing fungicides are likely to cause pesticide damage to peach, plum, and others; dimethoate emulsifiable concentrate is likely to cause pesticide damage to plum blossom, elm-leaved spirea, peach, ornamental peach, Chaenomeles speciosa, cherry blossom, and others; dichlorvos emulsifiable concentrate is also likely to cause pesticide damage to rhododendron, cherry blossom, plum blossom, and others. For the same flower, generally speaking, the seedling stage, tender shoots, and tender leaves are prone to pesticide damage. The flowering period is even more sensitive to the reaction of pesticides. Therefore, spraying pesticides during flowering easily causes flower drop and fruit drop.

(3)    Influence of environmental conditions.

Applying pesticides under high temperature has a good effect, but excessively high temperature easily causes pesticide damage. For example, lime sulfur mixture used in summer under high temperature (exceeding 30°C) is very likely to cause pesticide damage. The influence of humidity on some pesticides is also obvious. For example, arsenic agents and Bordeaux mixture are prone to cause pesticide damage under rainy and high-humidity conditions. Therefore, pesticide application should depend on the weather and be used flexibly.

①    Toxicity to natural enemies. After the application of many broad-spectrum pesticides, they not only kill pests and pathogens, but also kill natural enemies of pests, thereby causing pest resurgence. The solutions are:

Use selective pesticides. For example, ovotran, dicofol, and others have no effect on general insect natural enemies (such as ladybugs, hoverflies, predatory mites, Trichogramma, and others), so using such acaricides to control mites is very safe for natural enemies. Trichlorfon has very low toxicity to ladybugs and their larvae and eggs, and is also relatively safe for parasitic wasps and braconid wasps. Another example is that botanical pesticides are mostly less lethal to natural enemies. Applying tobacco water is relatively safe for ladybugs, mirids, lacewings, predatory mites, parasitic wasps, and others. Rotenone has little effect on adult ladybugs and parasitic natural enemies.

Choose a suitable pesticide application period. For example, applying pesticide when parasitic wasps are still inside the host body will only kill the pests. Another example is that before artificially releasing natural enemies, first apply pesticides with a short residual effect period, and after the pesticide toxicity disappears, artificially release natural enemies.

②    Toxicity to humans. Pesticides are mostly toxic to humans and livestock to a greater or lesser extent. Therefore, attention must be paid to the safety of humans and livestock. Before applying pesticides, on the one hand, it is necessary to learn and master the toxicity of various pesticides and the precautions for use; on the other hand, protective work should be done well. During application, the original pesticide or liquid medicine must not touch the skin. If it does, wash it immediately with soapy water. When spraying, wear a mask and spray in the downwind direction to prevent the liquid medicine from splashing onto the face and inhaling toxic gas. Do not rub the eyes during operation. The tools used should be washed immediately after use and properly kept for future use. After each application, wash hands with soap as a precaution. If poisoning symptoms occur due to carelessness, immediately take detoxification measures, and if necessary, send the person to the hospital for treatment as soon as possible.

What is the cultivation method for petunia? What are its growth habits, and how can disease and pest invasion be prevented?

Everyone is familiar with petunia. We generally also call it morning glory because the flower shape closely resembles a trumpet. Double flowers are spherical, with white, purple, or various red flowers, very beautiful. When grown at home, it can be used as a potted plant, with a brilliant and pleasing landscape. Today I will take everyone to learn about how petunia is cultivated, what growth habits it has during cultivation, and how to prevent disease and pest invasion.

Cultivation techniques:

Growth habits:
It likes a warm environment with sufficient sunlight. It is not tolerant of frost and fears waterlogging. Its suitable growth temperature is 13-18°C. In winter, the temperature should be 4-10°C. If it is below 4°C, plant growth stops. In summer, it can withstand high temperatures above 35°C. During the peak growth period in summer, sufficient water is needed. Especially in the high-temperature summer season, watering should be done in the morning and evening to keep the pot soil moist. However, in the plum rain season, there is a lot of rain, which is very unfavorable to the growth of petunia. If the pot soil is too wet, the stems and leaves are prone to leggy growth, and if there is a lot of rain during the flowering period, the flowers easily fade or rot.

If the pot soil has standing water for a long time, the roots will rot and the plant will die. Therefore, potted petunia should use loose, fertile, and well-drained sandy loam. It is a long-day plant, and the growth period requires sufficient sunlight. Under normal light conditions, it takes about 100 days from sowing to flowering. When cultivating petunia in greenhouses in winter, under low-temperature and short-day conditions, the stems and leaves grow very luxuriantly, but flowering is difficult. When spring enters long-day conditions, flower buds quickly differentiate from the tips of stems and leaves.

Precautions:

From the start of temporary planting until before flowering, it is necessary to keep pinching (topping and pinching off growing tips). Do not be reluctant to pinch. The flower ball is created by pinching. Topping and pinching off growing tips can promote branching and increase flower quantity.
The flower pot is placed in the window sill railing. When the flower branches inside grow to a certain extent, find a way to lay them outside to increase the thickness of the flower branches, that is, to increase flower quantity. This is a method I came up with because there is not enough space. If there is sufficient space, a large flower ball can be produced, but inside you cannot see the effect from outside.
Ice Lavender, Picotee Purple, Picotee White, and Pink Morning Light are all varieties that easily fill a pot and are relatively easy to grow. If the space is a bit more spacious, the middle 2 varieties can also produce the effects of the sides, really wronging Picotee Purple and Picotee White. Generally, sowing is in mid-March. If things go smoothly, temporary planting is in mid-April, final planting is in mid-May, and flowering is from around June 20 to the end of September.

Prevention and control of diseases and pests:

The main disease of petunia is damping-off in the seedling stage (controlled with 800-1000 times liquid of chlorothalonil or thiophanate-methyl), and stem rot during the growth period; the main pests are diamondback moths, aphids, leaf-roller moths, and others, especially common in National Day flower production. When aphids appear, it is generally not suitable to spray fenvalerate, as it easily causes pesticide damage and affects growth. V. Quality when leaving the nursery. For potted flowers produced in winter, use 12 cm caliber nutrition pots, and the crown width is generally between 20-25 cm, with a neat, full plant shape and uniform flowering; for potted flowers produced in summer, use 10 cm caliber nutrition pots, and the crown width is generally 15-18 cm. Petunia can be transported over long distances.

The above is all the content we learned today about how to grow petunia in pots. We hope flower enthusiasts will find this article helpful after reading it. If you want to learn more about herbaceous plants, please continue to follow our Succulent Flower Garden, which will provide you with more related content!