4 b chapter diseases of mulberry and their management

Diseases of Mulberry

1. Diseases of Mulberry and their management By, Nayana , B. P. Msc . (Agri.) SRF UAHS, Shivamogga

2. MULBERRY DISEASES Fungi, Bacteria, Virus and Nematode chiefly cause many diseases of mulberry and they take a heavy toll of mulberry leaf yield. Feeding the leaves of infected plants to silkworms adversely affects their growth and health resulting in partial or sometimes complete failure of cocoon crops.

3. Fungal diseases: Cercospora leaf spot: Cercospora moricloa ( Cooke ) Sacc. (O – Moniliales : Class– Deutromycetes ) Period of occurrence The disease occurs during South–West monsoon and severe between Aug– Oct The loss due to the disease ranges from 10 – 20 per cent depending on the age of the garden. Symptoms and nature of damage Initial symptoms of the disease are small light brown specks on leaves. These specks later enlarge into nearly circular, dark brown lesions with chlorotic margin. Severely infected leaves turn yellow and fall off pre maturely.

4. Symptoms and nature of damage Brownish necrotic, irregular spots appear on the leaf surface. Spots enlarge, extend and join together leaving characteristic ‘shot hole’. Leaves become yellow and wither off as disease becomes severe Factors responsible for spreading of the of the disease The disease is air borne dispersing by uredospores through water droplets and wind current. Temperature of 22-26° C and high relative humidity above 70 % are favorable for the disease development.

5. Control All the diseased leaves should be collected and burnt prior to rainfall that avoids further spread in the garden through rain water. Spray 0.2% Carbendazim (2 g/ lt of water) twice at 15 days interval. Waiting period of this chemical is 15 days. So leaves can be fed to worms after 15 days of spraying.

6. Powdery mildew Phyllactinia corylea (Pers .) Karst (O– Erysiphales : Class – Ascomycetes ) Period of occurrence The disease occurs during Aug- Jan Maximum severity is noticed during Oct- Dec The loss incited by the disease ranges from 10 – 15 per cent Symptoms and nature of damage White powdery patches appear on the under surface of leaves. Under favorable conditions, the symptom may progress to form an almost total white superficial covering on the under surface of leaves. Infected leaves turn yellow, lose the moisture and crumble if crushed finally leads to defoliation.

7. Symptoms and nature of damage White powdery patches appear on the lower surface of the leaves. The corresponding portions on the upper surface develop chlorotic lesions. When severe, the white powdery patches turn to brownish-black; the leaves become yellow, coarse and loose their nutritive value Factors responsible for spreading of the disease: The disease is air borne spreading by conidia primarily through wind current. Temperature of 24 - 28º C and high relative humidity (75-80 %) are responsible for infection and disease development.  

8. Control Adopting wider spacing facilitates adequate aeration and penetration of sunlight helps to reduce disease severity. Spray 0.2% Carbendazim (2 g/ lt of water) twice at 15 days interval. Waiting period of this chemical is 15 days. Spraying of 0.2 % Karathane ( Dinocap 30% EC) / Bavistin on the lower surface of the leaves. Safe period 5 days or spray Sulfex (80WP) 0.2%, safe period 15 days.

9. Period of occurrence This is most common during winter months of Nov.- Jan. The loss due to disease is about 5 per cent. Symptoms and nature of damage Leaf rust Cerotelium fici ( Cast.) Arth . And Peridiospora mori ( O – Uredinales : Class – Basidiomycetes ) Numerous, small, light brown specks appear on the under surface of leaves. Which later turn into dark brown rusty spots.

10. Control All the diseased leaves should be collected and burnt prior to rainfall that avoids further spread in the garden through rain water. Spray 0.2% Carbendazim (2 g/ lt of water) twice at 15 days interval. Waiting period of this chemical is 15 days. So leaves can be fed to worms after 15 days of spraying.

11. Stem canker Fungus Lasiodiplodia theobromae This is a serious disease in south India in nurseries killing the cuttings. Symptoms and nature of damage In nurseries Failure of cuttings to sprout, sudden withering and death of sprouts, discolouration and drying of stems and buds above the soil, rotting and peeling of bark, black mycelial strands of the infected stem portion. On established garden Greyish brown discoloration of the bark, delayed sprouting, death of buds and sprouts and death of plants.

12. Symptoms and nature of damage Control Rouging of infected cuttings and saplings Field should be kept clean. Destruction of crop residues Pretreatment of cuttings with 0.2% Carbendazim (2 g/ lt of water) for 30 minutes and followed by spray after 15 days of planting  

13. Root rot disease Fusarium solani and F. oxysporum ( O- Tremellales : Class – Basidiomycetes ) The disease appears in all types of soil and climate throughout the year. The loss is about 2 – 10 per cent. Symptoms and nature of damage Sudden withering off of leaves takes place followed by dying of the plant. The roots are rotten. Control Uproot the severely affected plants . While planting the rooted saplings, dip them in 0.2% Carbendazim solution for half an hour and planting in pits with 5g Mancozeb. For existing plantation, apply 5g Mancozeb around the plant and cover it with soil.

14. Fungal leaf blight Pathogen: Alternaria alternata , Fusarium pallidoroseum Occurrence; The disease starts progressing 45th DAP becoming severe on 70th DAP and is prevalent during summer and rainy seasons. Crop loss 10-12% Symptoms The disease starts as browning/ blackening of leaves starting either from the leaf tip or edges of leaf lamina in the form of isolated irregular brown coloured patches. As the disease spreads the entire leaf surface is affected resulting in fall of leaves.

15. Factors responsible for spreading of the disease The disease is air borne dispersing by conidia through water droplets and wind current. Temperature of 25-30º C and relative humidity of 40-60 % are favourable for the outbreak of fungal blights. Control measures to be adopted Remove the infested leaves, collect in a polythene bag and destroy by burning. Follow wider spacing of plantation or paired row planting system Spray 0.2 % Indofil M-45 (Mancozeb 75 % WP) solution on the leaves.

16. Bacterial diseases   Bacterial leaf spot or bacterial blight Pseudomonas mori Boyer and Lambert ( O – Pseudomonodeles : Class – Schizomycetes ) Period of occurrence The disease occurs during June – December. Yield loss is around 1- 2 per cent. Symptoms and nature of damage Lesions initially consist of small, irregular, water soaked areas on the under surface of leaves. Later , they enlarge and become dark brown to black necrotic lesions. If young leaves are infected, they curl and drop off, while medium aged leaves turn yellow prior to defoliation .

17. Factors responsible for spreading of the disease Though the disease is air and soil-borne, soil is the primary source of infection and secondary infection–irrigation and cultivation practices.  High temperature (28-30 ºC) and high humidity (more than 80%) are favorable for the disease development.  Control   Infected leaves should be removed and burnt to reduce the inoculum load in the garden. Follow wider spacing of plantation (90 cm x 90 cm) or paired row planting system  [(90 +150) × 60 cm] Spray 100 ppm Streptocycline solution (1 g in 10 lt of water) on leaves twice at 4 days interval or 0.2% Indofil M-45 (Mancozeb 75% WP) on the leaves.

18. Root knot disease Meloidogyne incognita ( Kofoid and White Chitwood ) (Sup family – Heteroderoidea ; O- Tylenchida , Class- Secernentia ; Phyllum - Nematoda ) Period of occurrence It occurs throughout the year, mainly in irrigated sandy loam soils having low organic matter. The loss due to disease is about 15 – 30 per cent. Symptoms and nature of damage The endoparasitic female nematode lays 400 – 500 oval shaped eggs in a sac on the roots. The young nematodes move freely in soil and enter the roots as result the root cells undergo excessive multiplication resulting in gall formation . The infected plant exhibit stunted growth, poor and delayed sprouting and reduces the leaf size and yield.

19. Symptoms and nature of damage Severely affected mulberry plants show stunted growth with low water moisture in leaves, later yellowing of leaf margins.  Formation of knots / galls on roots is the main indicator of the disease symptom.   Galls are spherical and vary in size; young galls are too small and yellowish-white in colour , old galls are big and pale brown. 

20. Factors responsible for spreading of the disease Disease spreads primarily through contaminated soil, farm implements and run-off irrigation. Planting of infected saplings along with other susceptible crops increases the disease intensity, some susceptible weeds in and around the mulberry gardens act as the secondary sources of infection Temperature between 27-30 ºC, soil moisture of less than 40 % and pH of 5 to 7 are favorable for the development of the root knot disease.

21. Control Saplings free nematodes infestation should be used. Deep ploughing helps in exposure of nematodes and their eggs to solar radiation and killed. Application of neem cake @2 MT/ha/year in 4 split doses reduces nematode infestation during intercultural operation or after pruning the plant or after leaf harvest by making the trenches of 10 –15 cm deep near the root zone of plant and cover with soil and irrigate. Furadon 3G (40 kg/ha) can be applied either I furrows or broadcast to the soil after light harrowing.

22. Root rot Rhizoctonia bataticola (= Macrophomina phaseolina ); Associated secondary microbes: Fusarium solani / F. oxysporum / Botryodiplodia theobromae Occurrence Through out the year in all types of soils especially when the soil moisture and organic matter in soil are low. Crop loss: 15 % and above depending on the soil health and climate. Symptoms Initially the above ground symptom of the disease appears sudden withering of plants and leaves fall off from the bottom of the branches and progressing upwards.

23. Symptoms The below ground symptoms include decaying of root cortex or skin, turn black due to fungal spores/ mycelium below the bark. The severely affected plants loose the hold in the soil and can be easily uprooted. On severity, the entire root system gets decayed and plants die. Affected plants after pruning, either fail to sprout or plant sprouted bears small and pale yellow leaves with rough surface.

24. Factors responsible for spreading of the disease The disease occurs in soils of high temperature (28 - 34ºC), low moisture (below 40 %) and low organic matter. The disease spreads primarily through contaminated soil, farm implements and irrigation. The secondary source of infestation is through diseased saplings, irrigation and cultivation practices. Control measures A target specific new formulation “ Navinya ” (herbal 80% & chemicals 20%) is used for the control of root rot disease of mulberry.

25. Method of application Prune off the dried shoots above 15-30 cm from ground. Make shallow ring around stump and apply the Navinya solution made by adding 10g of Navinya in 1 liter of water (i.e. 1 kg Navinya in 100 liter water; sufficient for 100 plants @ 1 liter/plant). Pour the solution over the pruned stump to drench completely. Cover with soil around the stump to prevent exposure to sunlight. Treat the surrounding mulberry plants also to prevent spreading of the disease.

26. Precautions to be taken Do not irrigate the treated mulberry plants during the first 4-5 days. Remove the dead mulberry plants and burn and expose the soil to sunlight. Plant the new saplings after dipping their roots in 0.2 % Navinya solution for 30 minutes before planting. Maintain optimum organic content >0.5% in soils by applying compost/ manure. During summer months irrigate the garden to keep the soil moisture around 50-60% to prevent the disease.

27. Deficiency symptoms of major nutrients Nitrogen Terminal growth of the plant is arrested and plant growth is stunted. Quick yellowing of the lower part of the leaf. Yellowing starts from the margin of the leaf which spreads throughout the leaves and finally whole plant becomes yellow. Corrective measures Soil application of 300kg N/ha in 5 split doses furrow system in irrigated / semi irrigated and six split doses for pit system.

28. Phosphorus Plant growth is ceased. In young leaves chlorosis occurs throughout the leaf and irregular lesions are formed below the margins. Severely affected leaves show scorching in the margin. Older leaves becomes yellow very fast and fall off pre maturely. Corrective measures 20kg/ha in two split doses. Foliar application of DAP (1%).

29. Potassium Terminal growth of the plant is ceased. Lower leaves become yellow and fall off pre maturely. Necrosis starts from margins, which spreads all around the leaf and leaves become totally yellow. Corrective measures 120kg/ha in two split doses. Foliar : MOP (1%).

30. Calcium ( Ca ) Plant growth is totally ceased and becomes weak and lodged Leaf shape is distorted and young leaves become more acute in shape. Necrosis starts in margin and tip of the leaves. Old leaves were severely affected and shows yellowing with mosaic green patches. Leaves start falling in pre-mature stage.

31. Other deficiency symptoms Zinc Stunted plant growth chlorosis of young leaves, bottom leaves with bleached spots or Whitish spots. Leaves colour becomes lemon yellow. Copper Leaf tip becomes white narrow and twisted, stunted growth, dieback of terminal bud, marginal chlorosis . Iron Typical intervenal chlorosis , papery white leaves with necrotic spot. Lower leaves turn golden yellow with dusky look .

32. Boron Resetting of terminal growth, death of terminal bud and cracked stem, bleaching of mid rib and vein. Molybdenum Undulating leaf surface necrotic spots along midrib, oozing of gum from mid rib. Manganese Thin foliage, dark green bands along the midrib, light green stripe between dark green veins, twigs with dieback symptom leaf tapering. Sulphur Oily spots on leaves, leaves turn yellow and fall off.

33. Corrective measures Foliar spray ZnSO 4 5gm/l FeSO 4 10 g/l Borax 2.5 g/l CuSO 4 2.5 g/l Mn 2.5 g/l or Sodium molybdate on 20 th and 40 th day after pruning. Add wetting agent teepol @ 0.5 ml/l for better adherence on the foliage.