Freesia
As a representative of perennial bulbous plants, Freesia (also known as Little White Orchid) is deeply loved by horticulture enthusiasts for its elegant flower posture. However, during the cultivation process, diseases such as brown spot and root rot frequently occur, directly affecting the quality of flowering. This article systematically sorts out the characteristics of three common diseases and their corresponding control measures, accompanied by high-definition symptom diagrams to help you accurately identify and scientifically deal with plant health issues.
Tips for Controlling Freesia Leaf Spot Disease
Recognition Features of Viral Diseases
The leaves show irregular yellow-green mottling, and brown necrotic spots will appear as the condition worsens. Infected plants exhibit growth stagnation, and the degradation of bulbs over the years leads to a sharp reduction in flowering, with a flowering rate decrease of over 60% in plants that have not been treated for three years or more.
Double Blocking of Transmission Pathways
Infected plants must be isolated and destroyed immediately, and plants within a 2-meter radius should be sprayed with a 40% omethoate emulsion 1500 times dilution to establish a protective zone. It is recommended to use virus-free seedlings from tissue culture for bulb selection, and soak them in a 0.5% potassium permanganate solution for 20 minutes before planting for disinfection. For aphid control, it is recommended to alternate the use of imidacloprid and matrine, spraying once a week for three consecutive weeks.
Response Plan for Freesia Sclerotinia Disease
Typical Symptoms of Fungal Infection
Initially, the base of the leaf sheath shows watery lesions, and later, black sclerotium blocks form inside the bulbs. The disease spreads rapidly when humidity is greater than 75% and the temperature is between 18-25°C, and if not treated in time, it can lead to infection in over 70% of the plants in the entire planting area.
Soil and Chemical Synergistic Management
Before planting, use pentachloronitrobenzene powder at a ratio of 1:30 to mix with soil for disinfection, and during the outbreak period, use 50% iprodione 800 times dilution for root irrigation treatment. For potted plants, it is recommended to replace the soil with new soil that has been sterilized by high-temperature steam, and for field planting, a three-year crop rotation system is needed.
Systematic Control of Freesia Root Rot Disease
Multi-Stage Lesion Manifestations
During the growing period, the leaves turn yellow from the bottom up, and during the storage period, the bulbs show brown sunken spots accompanied by a sour smell. The incidence of this disease in heavy clay soil is 3.2 times higher than in sandy loam soil, and the incidence rate during the rainy season is 45% higher than in the dry season.
Principle of Graded Treatment
Mild infections should be treated by浇灌 the roots with a 50% zineb 500 times dilution, once every 5 days for 3 times. For severely rotting bulbs,消毒 the affected area with quicklime, and it is recommended to use a mixture of metalaxyl-M and iprodione for soil sealing treatment.
By establishing a regular inspection system and a graded control system, the spread of the three major Freesia diseases can be effectively controlled. It is recommended to combine with the plant phenology, conducting preventive medication during the germination stage, leaf expansion stage, and bud formation stage, and using microbial fertilizers to enhance plant resistance, which can reduce the disease incidence rate by over 80%.