Turnips are a cherished root vegetable. Even robust turnips encounter challenges impacting health and yield. Understanding common issues helps identify and solve problems early. Proactive addressing ensures successful harvest.
Common Turnip Pests
Aphids, small insects, cluster on undersides of leaves. They feed by sucking plant sap, causing leaves to curl or yellow. Heavy infestations stunt growth and produce honeydew, attracting sooty mold. Water spray dislodges aphids; insecticidal soap suffocates them.
Flea beetles are tiny, dark insects chew small, circular holes in leaves. Young seedlings are vulnerable; damage can stunt or kill them. Floating row covers exclude flea beetles, and diatomaceous earth around plant bases deters them by abrasion.
Root maggots, larvae of small flies, tunnel into turnip roots, creating channels causing rot and stunted growth. Adult flies lay eggs at bases; larvae burrow into soil to feed on roots. Fine mesh netting prevents adult flies from laying eggs on seedlings. Crop rotation reduces soil-borne pest populations.
Slugs and snails are nocturnal feeders, leaving irregular holes in leaves and damaging roots, with a silvery slime trail. They thrive in moist conditions. Hand-picking slugs controls them; barriers of crushed eggshells or diatomaceous earth deter them.
Cutworms are gray-brown caterpillars feeding at night, severing young seedlings at the soil line. They curl into a C-shape when disturbed, hiding just below the soil surface during the day. Protecting seedlings with cardboard collars around the stem prevents cutworm damage.
Turnip Diseases
Clubroot, a fungal disease, causes swelling and distortion of roots. Infected plants often wilt and are stunted, as damaged roots cannot absorb water or nutrients. The disease can persist for years. Increasing soil pH to 7.0-7.2 with lime and good drainage suppresses the pathogen. Resistant varieties are the best long-term solution.
Powdery mildew appears as white, powdery patches on leaves. This fungal disease thrives in dry, humid conditions, restricting photosynthesis, causing yellowing and premature leaf drop. Good air circulation from proper spacing prevents its spread. Labeled fungicides control severe outbreaks.
Downy mildew presents as yellow or pale green spots on upper leaf surfaces, with fuzzy, purplish-gray growth underneath. Unlike powdery mildew, it prefers cool, moist conditions and spreads rapidly through splashing water. Affected leaves turn brown and die. Removing infected leaves limits spread. Selecting resistant turnip varieties significantly reduces risk.
Black rot, a bacterial disease, causes V-shaped yellow lesions beginning at leaf margins, progressing inward with black veins. Bacteria enter through wounds or natural openings, spreading systemically through the plant’s vascular system, leading to wilting and death. Good garden sanitation, including debris removal and avoiding overhead watering, prevents spread.
Damping-off is a common problem for turnip seedlings, causing rot at the soil line and collapse. This fungal disease affects young seedlings, especially in cool, wet, poorly drained conditions. Sterile seed-starting mix and adequate air circulation prevent damping-off. Avoiding overwatering creates an unfavorable environment for fungi.
Environmental and Cultural Issues
Turnips can prematurely flower, known as bolting, resulting in tough, bitter roots. Occurs with prolonged cold followed by warm weather, or inconsistent moisture. Planting climate-suited varieties and consistent soil moisture mitigates this stress.
Cracking or splitting roots results from inconsistent watering, especially a dry spell followed by sudden water. Rapid water uptake causes roots to expand faster than their skin, leading to splits. Consistent watering helps prevent this issue.
Woody or fibrous roots develop when left too long, becoming over-mature. Insufficient water or prolonged heat stress also contributes to this texture. Harvesting at optimal size ensures tender roots.
Small or poorly formed turnip roots result from overcrowding. Nutrient deficiencies or compacted soil restricting root expansion lead to undersized roots. Proper spacing, enriching soil with balanced nutrients, and loosening compacted soil improves root development.
Yellowing leaves indicate nutrient deficiency. Overwatering or poor drainage causes leaves to yellow as waterlogged soil deprives roots of oxygen. Testing soil for nutrient levels and ensuring well-draining soil is important.
Bitter taste in turnip roots reacts to heat stress or inconsistent watering. High temperatures cause an unpleasant flavor. Afternoon shade in hot climates and steady soil moisture helps produce sweeter roots.
Preventing Turnip Problems
Crop rotation disrupts pest and disease cycles, preventing annual replanting in the same spot and reducing soil-borne pathogen buildup.
Proper soil preparation ensures good drainage, adjusts pH for nutrient availability, and incorporates organic matter for enriched soil and improved structure.
Consistent, deep watering delivers moisture to the root zone, encouraging strong root development and preventing cracking.
Adequate spacing ensures good air circulation, preventing fungal diseases and reducing competition for resources.
Choosing resistant varieties reduces common diseases and pests, offering defense tailored to local conditions.
Regular monitoring allows early detection of pests or diseases, enabling prompt intervention and preventing widespread crop damage.
Maintaining good garden sanitation involves promptly removing diseased or infested debris, preventing pathogen and pest overwintering or spread.