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Diseases and Pest of food Plants

DISEASES & PESTS OF MULBERRY FOOD PLANTS

I. FOLIAR DISEASES

  • Leaf Spot

    Pathogen : Cercospora moricola

    Occurrence : It is more prevalent during rainy season followed by winter. The disease starts progressing 35-40 days after pruning (DAP)/leaf harvesting and becomes severe on the 70th DAP.

    Crop loss : 10-12 %

    Symptoms : 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 disease:

    • The disease is air borne spreading by conidia primarily through rain droplets.
    • Temperature of 24-26 ºC and 70-80 % relative humidity are most congenial for the disease development.

    Control measures to be adopted:

    • Spraying of 0.2 % Bavistin (Carbendazim 50% WP) solution on the leaves.
    • Safe Period: 5 days.
  • Powdery Mildew

    Pathogen : Phyllactinia corylea

    Occurrence : Disease is prevalent during winter and rainy seasons and progresses 40th DAP/leaf harvest becoming severe on 70th DAP.

    Crop loss : 5-10%

    Symptoms : 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.

    Control measures to be adopted:

    • Follow wider spacing of plantation (90 cm x 90 cm) or paired row planting system [(90 +150) × 60 cm]
    • 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.
  • Leaf Rust

    Pathogen : Cerotelium fici

    Occurrence : The disease is more prevalent during winter and rainy seasons. It starts progressing 45-50 DAP becoming severe on 70th DAP. The mature leaves are more prone to the disease

    Crop loss : 10-15%

    Symptoms : Initially, circular pinhead sized brown eruptive lesions appear on the leaves and later leaves become yellow and wither off.

    Factors responsible for spreading 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 favourable for the disease development.

    Control measures to be adopted:

    • Follow wider spacing of plantation (90 cm x 90 cm) or paired row planting system [(90+150) × 60 cm]
    • Avoid delayed leaf harvest
    • Spraying 0.2% Kavach (Chlorothalonil 75 % WP) on the leaves
    • Safe period: 5 days
  • Sooty Mould

    Pathogen : A group of fungi

    Occurrence : The disease is more prevalent during winter (August-December) season.

    Crop loss : 10-15%

    Symptoms : Thick black coating develops on the upper surface of the leaves.

    Factors responsible for spreading of the disease:

    • The disease occurs due to the presence of white flies in the mulberry field.
    • The fungi develop on the honey like substance produced by the whiteflies.
    • Temperature of 20-24° C and high relative humidity above 70 % are favourable for the disease development.

    Control measures to be adopted:

    • Spray 0.2% Indofil-M45 to check growth of saprophytic fungi
    • Foliar spray of 0.02% monocrotophos on 15th and 30th day after pruning to control white fly infestation.
    • Safe period: 15 days.

II. ROOT DISEASES

  • Root Knot

    Causal organism: Meloidogyne incognita (Nematode)

    Occurrence: The disease is out break through out the year and more common in sandy soils under irrigated conditions.

    Crop loss: 20 %

    Symptoms:

    • 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.

    Factors for spreading 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.

    Control measure:

    • Apply neem oil cake @ 800 kg/acre/yr in 4 split doses 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.
  • Root Rot

    Causal organism : Rhizoctonia bataticola (= Macrophomina phaseolina)

    Associated secondary microbes : Fusarium solani/ F. oxysporum/ Botryodiplodia theobromae

    Occurrence: Throughout 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.

    Above ground symptoms of root rot (yellowing/withering of leaves)

    • The below ground symptoms include decaying of root cortex or skin, turn black due to fungal spores/ mycelium below the bark (Fig 13).
    • 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.

    Factors for spreading 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 measure: A target specific new formulation “Navinya” (herbal 80% & chemicals 20%) is used for the control of root rot disease of mulberry

    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 10 g 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.

    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.

III. PESTS

  • Pink Mealy Bug

    Occurrence & Symptom : Pink mealybug, Maconellicoccus hirsutus (Green) causes deformity symptom in mulberry which is popularly called as Tukra. Leaves become dark green, wrinkled & thickened with shortened inter nodal distance resulting in bunchy top appearance/resetting of leaves. It occurs throughout the year, but severe during summer months. Mulberry leaf yield is reduced by 4,500 kg/ha/yr due to this pest.

    Control measures

    Mechanical control:

    Clip off the infested portion by secateur, collect in a polythene bag and destroy by burning. This will help in reducing the chances of recurrence of pest. This practice may be followed when the silkworms attain 4th age.

    Chemical control: Spray 0.2% DDVP 76% EC (@ 2.63 ml/lit water) 15–20 days after pruning. Safety period: 15 days.

    Biological control:

    Release predatory lady bird beetles Cryptolaemus montrouzieri @ 250 adult beetles or Scymnus coccivora @ 500 adult beetles in two equal splits at an interval of 6 months.

    Availability of predatory lady bird beetles: Pest Management Lab., CSR&TI, Mysore (ph. No.0821-2903285) cost: Rs 120 per unit.

  • Papaya Mealy Bug

    Occurrence & Symptom: The papaya mealy bug, Paracoccus marginatus is an exotic pest which infest a variety of crops such as papaya, guava, teak, vegetables, Jatropha, and weed plants like Parthenium, Sida, Abutilon etc. In mulberry its infestation causes malformation of affected portion, stunted growth of leaf, presence of red/black ants, honey dew secretion, growth of sooty mould, and outright killing of the plant. At present occurrence of papaya mealy bug is sporadic.

    CLASSICAL BIOLOGICAL CONTROL OF PAPAYA MEALYBUG

    • Release exotic parasitoid, Acerophagus papayae @1 vial per acre (1 vial= about 100 adult parasitoids).
    • Do not remove or destroy alternate host plants such as Parthenium, Sida, Abutilon, Jatropha etc., containing mummified mealybugs.
    • Do not spray any insecticide for its control, which may still worsen the situation.

    Note: Exotic parasitoids are available at National Bureau of Agriculturally Important Insects (NBAII), ICAR, Bangalore [opp: CBI, Ganganagar, Bangalore; phone no. 080-23511982/98]

  • Mulberry Leaf Roller

    Occurrence & Symptom : Incidence of Leaf roller, Diaphania pulverulentalis in mulberry starts with the onset of monsoon. It occurs from June to February but reaches peak during September – October months. The larva binds mulberry leaf blades by silken thread, stay inside & feed. Its feacal matter can be seen below the infested portion.

    Control measures

    Mechanical control: Remove the infested portion (along with the larva) by secateur, collect in a polythene bag and destroy by burning.

    Chemical control:

    • Spray 0.076% DDVP (@ 1 ml/lit water) 12 to 15 days after pruning. Safety period: 7 days.
    • Second spray of 0.5% commercial neem pesticide (0.03% Azadirachtin) @5ml/Lit water,10 days after first spray. Safety period: 10 days.

    Biological control : Release Trichogramma chilonis egg parasitoid @ 1 Tricho card/week (for 4 weeks). Do not spray any insecticide after the release of trichogramma parasitoids.

    (Note: Tricho cards are available on cost basis at Krishi Vigyan Kendra, Suttur, Nanjangud taluk, Mysore dist. or Parasite Breeding Lab., Dept. of Agriculture, [Near DC Office] Mandya)

  • Bihar Hairy Caterpillar

    Occurrence & Symptom : Incidence of Bihar hairy caterpillar, Spilarctia obliqua in mulberry starts with the onset of monsoon. It occurs throughout the year and in certain pockets it appears sporadically. Young larvae are gregariously found feeding on the underside of leaf giving an appearance of mesh and one can make out from distance. Grown up ones are solitary, very active, spread throughout the field and feed voraciously on the foliage.

    Control measures

    Mechanical/Physical control: Collect the egg masses or gregarious young caterpillars and destroy by dipping in 0.5% soap solution or by burning.

    Chemical control:

    • Spray 0.076% DDVP (@ 1 ml/lit water) 12 to 15 days after pruning. Safety period: 7 days.
    • Second spray of 0.5% commercial neem pesticide (0.03% Azadirachtin) @5ml/Lit water,10 days after first spray. Safety period: 10 days.

    Biological control: Release egg parasitoids Trichogramma chilonis @ 1 Tricho card/week for 4 weeks. Do not spray any insecticide after the release of trichogramma parasitoids.

  • Thrips

    Occurrence & Symptom : Thrips, Pseudodendrothrips mori, is a major pest in Tamil Nadu and minor pest in Karnataka & Andhra Pradesh. It occurs throughout the year and severe during summer (February - April). Both adults and nymphs lacerate the leaf tissues and suck the oozing sap. Affected leaves show streaks in early stages and yellowish/brown blotches in the advanced stage of attack.

    Control measures

    Mechanical/Physical control : Use sprinkler irrigation to disturb thrips population & eggs on the underside of mulberry leaves.

    Chemical control:Spray 0.1% Rogor (@ 3 ml/lit water) 15 days after pruning. Safety period: 20 days.

    Biological control:Release predatory lady bird beetles (Scymnus coccivora @ 500/acre).

  • White Fly

    The name white fly is derived from the whiter appearance of the adults and their tendency to fly when disturbed. Adults have a pair of floury wings which are usually white with a few veins. In the recent years outbreak of Dialeuropora decempuncta has occurred on mulberry in southern state of Kerala and now observed to severely infest mulberry in the irrigated belt of Karnataka covering Mysore and Mandya districts.

    Occurrence & Symptom : The spiraling of waxy material is the typical symptom of white fly attack. Prolonged dry spell followed by the hot humid weather favours the white fly flare up. Occur during the months March-June; October-December. Both nymphs and adults pierce and suck the sap from foliage and the damaged leaf become unfit for silkworm rearing.

    Control measures

    Mechanical/Physical control:

    • Use sprinkler irrigation to disturb white fly population.
    • Fix yellow sticky traps @ 75-80 traps/acre to trap the adults.

    Chemical control: Spray 0.076% DDVP (@ 1 ml/lit water) 12 days after pruning (safety period: 10 days) and second spray with 0.05% Rogor 30% EC @ 1.5 ml/lit (safety period: 20 days)

    Biological control : Release predatory lady bird beetles Cryptolaemus montrouzieri @ 250 adult beetles or Scymnus coccivora @ 500 adult beetles/acre.

    Source:

    Central Sericulture Research & Training Institute, Mysore, Karnataka>

DISEASES AND PESTS OF TROPICAL TASAR FOOD PLANTS

MAJOR FOLIAR DISEASES OF TROPICAL TASAR FOOD PLANTS (TERMINALIA.ARJUNA AND T.TOMENTOSA)

  • Leaf spot (Pestalotiopsis palmarum):

    The disease appears on any part of the blade as circular to irregular patches, sometimes delimited by veins. The infected leaves show characteristic copper brown spots, just above the fungal growth, on the upper surface. Usually these are 2-8 mm in diameter but sometimes more extensive. Affected leaves become brittle. The necrotic area becomes dry, shrunken and severed partly or entirely from the leaf as a hole. Severely infected leaves from which much of the dead tissue has fallen away present an extremely ragged or insect eaten appearance. Leaf yield loss due to leaf spot disease has been reported to be 8-12%.

    Leaf spot occurs during July to November all over India when high humidity and high temperature prevail in the atmosphere. At CTRTI, Ranchi disease incidence in both T.arjuna and T.tomentosa was first observed during the month of June which increased steadily in the subsequent months and reached at its peak during the month of October. The disease shows positive correlation with relative humidity and rainfall. At R.T.R.S., Dumka, Baripada and Warangal r-value for RH was 0.888, 0.468 and 0.551, respectively. The r-value for rainfall was 0.455 at Dumka and 0.789 at Warangal.

    Management:

    • Proper cultural operations and field sanitation.
    • Plucking and burning of diseased leaves.
    • Spray of Carbendazim @ 0.1% or 0.5% Biltox or 0.5% Diathane M-45.
  • Black nodal girdling (Uredo spp):

    Disease symptoms begin from nectar gland and gradually spread to lower petiole region, in due course of time petiole and internodal regions get covered with black sooty spores along with mycelia, forming girdle like appearance. Thus, the entire leaf becomes unsuitable for silkworm rearing. In both Arjun and Asan plants, about 7-10% crop loss is reported.

    The disease occurs during rainy and winter seasons. This disease also appears during July at most of the places, increases up to January and then declines. At CTRTI, Ranchi disease started appearing in the month of August and found maximum during the month of October. Minimum temperature, rainfall and RH are found positively correlated. wherwas maximum temperature is negatively correlated.

    Management:

    • Proper cultural operations and field sanitation.
    • Plucking and burning of infected leaves.
    • Spraying of Carbendazim @ 0.1% (a systemic fungicide).
  • Powdery mildew (Phyllactinia terminaliae):

    As the name indicates white powder like patches appear on the ventral surface of leaves, afterwards appearance of distinct dot like structures is noticed on the powdery patches. Under advanced stage, the disease shows chlorotic symptoms on dorsal surface of leaves with curved lamina. Affected leaves become yellow and fall down prematurely. The crop loss has been reported to be 25-30% in Arjun and 8-10% in Asan, though qualitative loss may be much more.

    Powdery mildew is prevalent during October to December at most of the places. Maximum severity of powdery mildew at CTRTI, Ranchi in T. arjuna was observed during November. The disease occurs during October to March at all the places mainly due to change in minimum and maximum temperature. The disease is negatively correlated with temperature i. e., when the temperature is low, disease is more and vice versa. Rainfall is also negatively correlated.

    Management:

    • Proper cultural operations and field sanitation.
    • Plucking and burning of diseases leaves as and when they appear.
    • Spraying of Carbendazim @ 0.1% or 0.2% Dinocap or 0.2% Sulfex.
  • Leaf Curl (Copper deficiency):

    This disease is believed to be caused by deficiency of copper. Withering of leaves is observed in young and tender leaves, which show crinkling soon after expansion from the buds. Leaves exhibit boat shaped form due to folding of the leaflet along the midrib. Venation pattern shows tendency of conversing towards the apex of lamina and shows deep serration. Chlorosis of leaf starts from the margin as a result the tip and margin start drying and withering.

    Leaf curl disease is prevalent during June/July to November/December at most of the places. It is positively and significantly associated with relative humidity (RTRS Bhandara: r= 0.640; Jagdalpur: r=0.564 and Warangal: r=0.744).

    Management:

    • Proper cultural operations and application of fertilizers.
    • Spray of 175 ppm Copper Sulphate or 0.5%.Biltox.

    A calendar of occurrence of foliar diseases and different activities in Tropical Tasar culture areas is annexed as ready reckoner for management.

    Leaf spot disease

    Causal organism-Pestalotiopsis palmarum

    Class-Ascomycetes

    Black nodal girdling disease

    Causal organism- Uredo spp.

    Class- Basidiomycetes

    Powdery mildew disease

    Causal organism – Phyllactinia terminaliae

    Class-Ascomycetes

    Leaf curl disease

MAJOR PESTS OF TROPICAL TASAR FOOD PLANTS

  • Weevil (Myllocerus viridanus Fab.): Prevalence of weevil was observed throughout the year. High incidence of weevil was recorded from November to January. However, the peak period of its incidence was recorded in the month of August
  • Red Beetle (Tricliona picea Jacoby): The red beetle infestation was recorded from May to August where the peak period being in the month of August.
  • May-June Beetle (Anomala blanchardi): The incidence of May-June beetle was higher during April to August. While its peak infestation was recorded in the month of June and August.
  • Vapourer tussock moth (Notolophus antiqua Linn.): The higher prevalence of vapourer tussock moth was observed throughout the year except April, May, October and November months where the infestation is low.
  • Gall fly (Trioza fletcheri Monior): Gall infestation was also observed throughout the year and the peak infestation was recorded in the month of August. However, its infestation was very low or negligible in April, September and October months.
  • Stem borer (Aelosthes holosericea): The infestation of stem borer was observed throughout the year.

CONTROL MEASURES FOR PESTS OF TASAR HOST PLANTS

IPM package for the control of gall insect, Trioza fletcheri

Cultural: Pruning of tasar food plants at 4 to 6 feet height is to be postponed up to 30th April to minimize gall insect infestation.

Mechanical: Clipping the gall infested leaves of tasar food plants, collecting them into polythene / gunny bags and burning the same to avoid further spread of gall insect infestation; plucking and burning of gall infested tender leaves having eggs and matured gall infested leaves; collection and burning of old leaves having diapausing nymphs during winter (Dec- Feb.) and off rearing seasons.

Chemical: Soil application of Neem cake (dried and fine meshed @ 60 kg per acre) in the month of May before the onset of monsoon; foliar application of 15 ppm of Azadirachtin (10 ml per litre of water) three times from May to June at an interval of 15 days after sprouting (quantity of insecticides required-

Control of stem borer, Aelosthes holosericea

Mechanical: Collection and destruction of adults of stem borer insects; Collection and destruction of egg and grub with the help of sharp knife manually from bark and woody part of stem.

Chemical: Cotton soaked with 36% EC of Monocrotophos 0.07 % should be inserted in the holes made by the borer followed by mud plastering (quantity of insecticides required-1.94 ml per litre of water); plugging of holes with cotton soaked with 0.07% Monocrotophos (36% EC) followed by mud plastering (quantity of insecticide required-1.94 ml per litre of water).

Integrated package for the control of major defoliating pests

Cultural: Two times deep ploughing after silkworm rearing: Nov.-Dec. and March-April is to be done.

Mechanical: Collection and destruction of different developmental stages of insect such as eggs, grubs/larvae, pupae and adults of coleopteran and lepidopteran pests during morning and evening hours twice a week from the month of May to July.

Bio-pesticide:

Soil application of neem cake: Soil application of neem cake (dried and fine meshed @ 60 kg per acre in two split doses at 15 days interval before the onset of monsoon (1st dose – 15th May, 2nd dose-30th May).

Foliar application of Azadirachtin: Foliar application of 15 ppm Azadirachtin (10 ml per litre of water)once after 15 days of soil application of neem cake (15th June).

Source:

Central Tasar Research & Training Institute, Central Silk Board, Ranchi