1. EARLY AND LATE LEAF SPOT
DISEASE IN GROUNDNUT
Dr. Divya Mittal (Assistant Professor)
Department of Agriculture
MM(DU), Mullana
2. • Groundnut is the most important oilseed crop of India
• Crop suffers from a number of biotic stresses.
• Out of these leaf spot/ Tikka diseases is a major biotic constraint in realizing potential
yield of groundnut
3. Symptoms of Early Leaf Spot Symptoms of Late Leaf Spot
EARLY LEAF SPOT: Mycosphaerella arachidis (teliomorph/perfect
stage/ sexual stage)
(Cercospora arachidicola (anamorph/imperfect stage/ asexual stage)
• Spots appears about a month earlier than LS
• Spots are circular to irregular, 1-10mm in diameter and surrounded
by yellow halo.
• Spots are mostly produced on upper surface of the leaves. These
are necrotic , reddish brown to black on upper surface & light brown
on the lower surface
• Conidia are produced mostly on upper surface of leaves but
occasionally on lower surface
LATE LEAF SPOT: Mycosphaerella berkeleyii (teliomorph/perfect stage/
sexual stage) (Cercospora personata) (anamorph/imperfect stage/
asexual stage)
• Spots appears about a month later than ES.
• Spots are circular to irregular, 1-6mm in diameter and are not
surrounded by yellow halo.
• Spots are mostly produced on lower surface of the leaves. Colour of
the spot is carbon black
• Conidia are restricted to the lower, conidiophores are sparse and are
produced in concentric rings.
• Concentric rings of conidia macroscopically visible on the lower
surface.
4. Symptoms
• The symptoms of two pathogens may occur simultaneously on the same
leaf.
• Lesions first appear as a chloratic lesions about 10 days after spore
deposition.
• Mature sporulating lesions are visible about 15 days after spore
deposition.
• Beginning- on leaf only • Later-on stem also
5. EARLY LEAF SPOT: Mycosphaerella arachidis
(teliomorph/perfect stage/ sexual stage)
(Cercospora arachidicola (anamorph/imperfect
stage/ asexual stage)
Mycelium : intercellular becoming intracellular in
later stage, lack in haustoria, dark brown in colour
Conidiophores : 5 to many, yellowish brown,dark
at base, unbranched, continuous or with 1 or 2
septa
Conidia : subhyaline, pale yellow, often curved, 1
to 12 septate, round at base and subacute at tip.
Photos are collected by A. Surendhar (2017)
6. LATE LEAF SPOT: Mycosphaerella berkeleyii
(Cercospora personata)
Mycelium : septate, intercellular, branched
haustoria, stroma dense and
pseudoparanchymatous.
Conidiophores: pale to olivaceous brown in
colour, one to 3 geniculated or not, aseptate or
continuous, simple or rarely branched emerging
through ruptured epidermis in dense fascicle.
Conidia: cylindrical, olivaceous, straight or
slightly curved, mostly 3-4septate, rounded at
apex, base shortly tapered.
Photos are collected by A. Surendhar (2017)
8. Disease Cycle
• Ascospores and Conidia present in crop residue are most important
primary inoculum
• Secondary spread of the spore through wind and water splash.
12. MANAGEMENT
Cultural method: Summer deep ploughing • weed management, crop rotation • eradication of volunteer
groundnut plants • field sanitation, soil solarisation • use of disease free seed material • apply optimum dose of
N, P fertilizers • use of resistant varieties ()
Chemical method: • seed treatment with 2g carbendazim or thiram per kg of seed. • soaking of seeds in 0.5%
CuSO4 –half an hour • spraying of carbendazim 0.1% or mancozeb 0.2% or chlorothalanil 0.2% (repeat 15
days after 1st spray). Propiconazole 0.1 % and hexaconazole 0.2% have also been found effected against this
disease.
Biological method • Soil application of 2 kg/ha Trichoderma viride mixed with 25 kg FYM. • Seed treatment with
Pseudomonas fluorescence @10 g/kg of seed. • Foliar spray of 2 % Trichoderma viride or Pseudomonas
fluorescence
Editor's Notes
Most commercially grown peanuts are used for the extraction of their oil which is used in cooking. The by product of oil extraction is a pressed cake which is used as an animal feed and also in the production of peanut flour. Raw kernels are also commonly roasted and eaten as a snack food. Peanuts are a great source of protein, packing more than 7 grams into each 1-ounce (28-gram) serving (1Trusted Source).
Protein is important for growth and development, as well as for wound healing, tissue repair, immune function, and more (2Trusted Source).,
It’s also crucial for increasing strength and supporting muscle growth, especially when paired with resistance training (3Trusted SourceTrusted Source).
According to one study, taking a peanut powder supplement increased muscle mass
The pathogen survives for a long period in the infected plant debris through conidia, dormant mycelium and perithecia in soil. The volunteer groundnut plants also harbour the pathogen. The primary infection is by ascospores or conidia from infected plant debris or infectd seeds. The secondary spread is by wind blown conidia. Rain splash also helps in the spread of conidia.
Fungi reproduce asexually by fragmentation, budding, or producing spores. Fragments of hyphae can grow new colonies. Mycelial fragmentation occurs when a fungal mycelium separates into pieces with each component growing into a separate mycelium. Somatic cells in yeast form buds. During budding (a type of cytokinesis), a bulge forms on the side of the cell, the nucleus divides mitotically, and the bud ultimately detaches itself from the mother cell.
The most common mode of asexual reproduction is through the formation of asexual spores, which are produced by one parent only (through mitosis) and are genetically identical to that parent. Spores allow fungi to expand their distribution and colonize new environments. They may be released from the parent thallus, either outside or within a special reproductive sac called a sporangium.
Sexual reproduction introduces genetic variation into a population of fungi. In fungi, sexual reproduction often occurs in response to adverse environmental conditions. Two mating types are produced. When both mating types are present in the same mycelium, it is called homothallic, or self-fertile. Heterothallic mycelia require two different, but compatible, mycelia to reproduce sexually.
Although there are many variations in fungal sexual reproduction, all include the following three stages. First, during plasmogamy (literally, “marriage or union of cytoplasm”), two haploid cells fuse, leading to a dikaryotic stage where two haploid nuclei coexist in a single cell. During karyogamy (“nuclear marriage”), the haploid nuclei fuse to form a diploid zygote nucleus. Finally, meiosis takes place in the gametangia (singular, gametangium) organs, in which gametes of different mating types are generated. At this stage, spores are disseminated into the environment.
