DISEASES OF LINSEED – Agricultural study materials

1. Rust –Melamspora lini

Symptoms

The rust may attack all the aerial parts of the plant including the capsules. Diseased plants produce bright orange uredo pustules on both surfaces of leaves. The infected leaves die prematurely.

Epidemiology

Cool temperature and high RH favours disease development.

Mode of Spread and Survival

The pathogen is Soil-borne and spreads by uredospores and teleutospores

Management

• Spray fungicides like Mancozeb @ 1.0 kg/ha or Tridemorph 0.1%
• Seed treatment with Oxycarboxin @ 0.1%
• Avoid excess use of nitrogenous fertilizers
• Grow resistant varieties like K2, Neela, Neelum.

2. Wilt – Fusarium oxysporum f.sp. lini

Symptoms

The disease attacks all growth stages of plant. The edges of cotyledons in young seedlings roll inwards and the seedlings die. On the leaves, small, ill-defined, dark green or brownish spots appear followed by drooping of upper portion of the plant and shrivelling of leaves that eventually results in death. When the basal stem and root of infected plants are split open, a black discolouration of vascular tissues is also noticed.

Mode of Spread and Survival

The pathogen is seed-borne and soil-borne and they survive in infected plant debris.

Epidemiology

Low soil moisture and dry weather favours the disease.

Management

• Use of Pseudomonas sp. can suppress wilt
• Crop rotation
• Seed treatment with Thiram or Captan @ 2.0g/kg  

3. Powdery mildew – Oidium lini

Symptoms

Disease symptoms appear in the form of dirty white floury patches on both sides of leaves. The leaves are covered with thick powdery masses, become curled, twisted, droop and die.

Epidemiology

Cool temperature & high RH favours the disease development.

Mode of Spread and Survival

The pathogen is soil-borne and they survive as ascospores which perennate in soil.

Management:

• Application of sulphur or wettable sulphur @ 0.2%

4. Alternaria leaf spot- Alternaria lini

Symptoms

The initial symptom of the leaf spot is the failure of the bud to open during day time and there is an appearance of minute dark black spots near the calyx. The floral parts shrink and rot. When capsules are affected they give a burnt appearance and in severe case plants may die.

Mode of Spread and Survival:

The pathogen is wind-borne and they survive in plant debris.

Epidemiology

The temperature between 26-30^o C and humid conditions favours the disease.

Management

• Seed treatment with Thiram @ 2.5g/kg seed.
• Spraying Mancozeb 0.2% and Bordeaux mixture 1.0 % before flowering minimizes the infection