How to Grow Kohlrabi in Illinois: Doctor Intelligence (Diseases) – Complete How-To
In the realm of agriculture and human welfare, the cultivation of kohlrabi in Illinois holds a unique importance. Kohlrabi, a member of the cabbage family, is a versatile and nutrient-dense vegetable that can thrive in the Midwestern climate, providing a valuable addition to local food systems and contributing to the overall well-being of the community. In this comprehensive guide, we’ll delve into the ins and outs of growing kohlrabi in Illinois, with a particular focus on identifying and managing common diseases that may arise during the cultivation process.
Understanding Kohlrabi
Kohlrabi, often referred to as the “German turnip,” is a root vegetable that grows above the ground, forming a bulbous stem with leaves radiating from the top. While the leaves and stems are edible, the bulb is the primary focus of cultivation, offering a crisp texture and a flavor reminiscent of a cross between broccoli and cabbage.
In Illinois, kohlrabi thrives in the temperate climate, with cool spring and fall seasons providing the ideal growing conditions. The vegetable can be grown both in open fields and in protected environments, such as greenhouses or hoop houses, allowing for extended season cultivation and year-round availability.
Site Selection and Soil Preparation
Choosing the right location for your kohlrabi patch is crucial. Kohlrabi prefers well-drained, fertile soil with a pH range of 6.0 to 7.5. Avoid areas with a history of clubroot or other soil-borne diseases, as these can significantly impact the growth and health of your crop.
Prepare the soil by incorporating ample organic matter, such as compost or well-rotted manure, to improve drainage and nutrient content. This will create the ideal growing environment for your kohlrabi plants. Additionally, conduct a soil test to ensure the proper balance of essential nutrients and adjust accordingly.
Planting and Care
Kohlrabi can be grown from seed or transplanted from seedlings. For best results, start seeds indoors 4-6 weeks before the last expected frost date, then transplant the seedlings into the prepared garden beds or raised rows. Ensure the plants are spaced 8-12 inches apart, with rows 18-24 inches apart, to allow for proper air circulation and easy management.
Consistent moisture is crucial for kohlrabi cultivation, so be sure to water your plants regularly, especially during periods of drought. Aim to keep the soil consistently moist, but avoid waterlogging, as this can lead to root rot and other moisture-related diseases.
Regularly monitor your kohlrabi plants for signs of pests or diseases, and be proactive in addressing any issues that may arise. Applying a layer of organic mulch around the base of the plants can help suppress weed growth, retain soil moisture, and provide a barrier against soil-borne diseases.
Common Diseases and Management
As with any crop, kohlrabi in Illinois is susceptible to various diseases that can impact its growth and yield. Let’s explore some of the most common ailments and effective management strategies:
Clubroot
Clubroot is a soil-borne disease caused by the pathogen Plasmodiophora brassicae, which targets members of the cabbage family, including kohlrabi. Symptoms include swollen, deformed roots and stunted plant growth. To manage clubroot:
- Avoid planting in areas with a history of clubroot infection.
- Maintain soil pH between 7.2 and 7.5 to make the soil less favorable for the pathogen.
- Rotate crops to break the disease cycle, avoiding planting brassicas in the same location for at least 3-4 years.
- Consider using resistant cultivars, if available, to minimize the impact of the disease.
Powdery Mildew
Powdery mildew is a fungal disease that can affect the leaves and stems of kohlrabi plants. It appears as a white, powdery growth on the plant surfaces. To manage powdery mildew:
- Provide adequate air circulation around the plants, either through spacing or the use of fans.
- Apply a baking soda or neem oil-based fungicide at the first signs of the disease.
- Remove and dispose of severely infected leaves to prevent the spread of the pathogen.
Bacterial Soft Rot
Bacterial soft rot is a common issue that can affect the kohlrabi bulb, causing it to become mushy and foul-smelling. This disease is often caused by the bacterium Erwinia carotovora. To manage bacterial soft rot:
- Avoid planting in areas with poor drainage or high soil moisture levels.
- Ensure proper spacing and air circulation around the plants to promote drying.
- Promptly remove and dispose of any infected plants or plant parts to prevent the spread of the disease.
- Consider using a copper-based fungicide or a biological control agent, such as Bacillus subtilis, to suppress the bacterial growth.
Alternaria Leaf Spot
Alternaria leaf spot is a fungal disease that can cause circular or irregular brown spots on the leaves of kohlrabi plants. If left unchecked, it can lead to defoliation and reduced plant vigor. To manage Alternaria leaf spot:
- Maintain good air circulation around the plants to discourage fungal growth.
- Apply a protective fungicide, such as a copper-based or a biological product, at the first signs of the disease.
- Remove and dispose of any heavily infected leaves to prevent the spread of the pathogen.
Damping-Off
Damping-off is a soil-borne disease that can affect kohlrabi seedlings, causing them to wilt, collapse, and die. It is often caused by fungi such as Pythium, Rhizoctonia, or Fusarium. To manage damping-off:
- Use well-draining, sterile potting mix when starting seeds indoors.
- Provide adequate air circulation and avoid overwatering the seedlings.
- Consider using a biological seed treatment or a fungicide to protect the seedlings.
- Ensure proper soil preparation and drainage in the garden bed to discourage the growth of damping-off pathogens.
Harvest and Storage
Kohlrabi is typically ready for harvest when the bulb reaches 2-4 inches in diameter, approximately 50-60 days after planting. Gently pull or cut the plants at the soil line, taking care to remove any dirt or debris from the bulb. Kohlrabi can be stored in the refrigerator for up to 2-3 weeks, or it can be preserved through canning, freezing, or fermenting for longer-term use.
Conclusion
Growing kohlrabi in Illinois can be a rewarding and valuable endeavor, contributing to the overall agricultural landscape and the well-being of the local community. By understanding the unique growing requirements of this versatile vegetable and being proactive in managing common diseases, Illinois farmers and home gardeners can cultivate a bountiful and nutritious kohlrabi crop. With the right knowledge and implementation of best practices, the cultivation of kohlrabi can become an integral part of the state’s sustainable food system, promoting both human and environmental health.
