Spring greenhouse disease prevention is essential for a successful growing season, particularly as the days become sunnier. Canadian greenhouses, especially in southern Ontario, British Columbia, and Quebec, are in full spring production by mid-April, cycling through winter propagation and focusing on tomatoes, peppers, cucumbers, strawberries, and ornamentals. They rely on supplemental lighting and climate control to maintain optimal temperatures.
For warm-season crops, spring transplant rotations begin in March for leafy greens, April for tomatoes, and May for peppers, ensuring a continuous supply despite fluctuating outdoor temperatures. However, moderate spring temperatures, high humidity, and dense canopy cover create ideal conditions for pathogens like Leveillula taurica, Botrytis cinerea, Phytophthora infestans, and Fusarium oxysporum. This necessitates precise environmental control and proactive disease surveillance within an Integrated Pest Management (IPM) framework.
Disease prevention in bell peppers: Powdery mildew and fusarium
In April, Leveillula taurica powdery mildew exploits cooler nights and warm daytime temperatures to establish infections in pepper plants. Greenhouse areas with high humidity accelerate the development and spread of the disease. Fusarium oxysporum is another concern, germinating from contaminated media and infecting plants as soil temperatures rise.
Challenges include the endophytic nature of Leveillula taurica, which spreads undetected for weeks, leading to canopy loss and reduced photosynthesis. Early lesions might be mistaken for nutrient deficiencies, delaying management. To manage these issues, maintaining relative humidity below 75%, sanitizing tools and benches, and rotating mildew-tolerant pepper varieties are recommended strategies.
Disease prevention in tomatoes: Late blight insights
Phytophthora infestans, responsible for late blight, thrives in spring microclimates with high humidity and moderate temperatures. It can rapidly infect plants, causing lesions and defoliation. Volunteer tomato plants and cull piles often serve as primary inoculum sources.
Challenges include the quick infection process and the emergence of resistant strains, which sustain disease pressure. Effective management involves maintaining canopy temperatures, ensuring proper ventilation, and using sanitation protocols to reduce inoculum sources. Regular monitoring and testing for latent P. infestans are crucial.
Disease prevention in cucumbers: Pythium root rot monitoring
Pythium aphanidermatum can proliferate in spring, especially in recirculating systems with warm solution temperatures. It causes root browning and wilting, spreading through contaminated nutrient solutions. Elevated pH and algal growth exacerbate the issue.
Preventive measures include maintaining nutrient solution pH to limit algal blooms, flushing lines to disrupt biofilms, and conducting regular diagnostic monitoring. These steps help reduce inoculum loads and manage the disease effectively.
Disease prevention in strawberries: Gray mold and Neo-P
Indoor strawberry production faces challenges from Botrytis cinerea (gray mold) and Neopestalotiopsis spp. in spring. High humidity and extended leaf wetness favor these pathogens, leading to flower and fruit infections.
Challenges include concurrent outbreaks and rapid spread through irrigation and worker movement. Management involves reducing humidity, removing infected material, and ensuring planting material is disease-free. Regular testing helps confirm pathogen presence and guide interventions.
Disease prevention in ornamentals: gray mold and bacterial speck
Ornamentals in greenhouses are susceptible to Botrytis cinerea and Pseudomonas spp., which thrive in humid conditions. These pathogens cause blight and leaf spots, spreading rapidly in dense canopies.
Challenges include dual pathogen pressure and moisture hotspots that facilitate spread. Management protocols focus on maintaining low humidity, improving air circulation, and rigorous sanitation. Monitoring and diagnostics help confirm pathogen presence and inform control measures.
IPM and summer prep for greenhouses
Transitioning from spring to summer requires integrating testing and analytical services into IPM strategies. Baseline testing before planting, routine monitoring, and diagnostic scans help identify pathogen presence and nutrient imbalances. Adjusting environmental controls, sanitation practices, and crop rotations based on test results ensures a robust, data-driven approach to disease prevention.
By combining rapid qPCR testing and comprehensive sequencing with deep-dive water, media, and tissue analytics, growers can effectively manage greenhouse conditions, maximize yield, and minimize chemical inputs. This approach ensures a smooth transition from spring propagation to a successful summer growing season.
For more information:
Healthy Hydroponics InnoTech
healthyhydroponics.ca/