Cucumber cultivation

Plant Diseases

Major diseases of Cucumber and their Management

Plant pathology (phytopathology) is the exploratory investigation of plant sicknesses brought about by pathogens (irresistible organic entities) and ecological conditions (physiological factors).[1] Organisms that cause irresistible ailment incorporate parasites, oomycetes, microbes, infections, viroids, infection like life forms, phytoplasmas, protozoa, nematodes and parasitic plants. Excluded are ectoparasites like creepy crawlies, parasites, vertebrate, or different irritations that influence plant wellbeing by utilization of plant tissues. Plant pathology likewise includes the investigation of pathogen ID, sickness etiology, malady cycles, financial effect, plant illness the study of disease transmission, plant infection safety, how plant sicknesses influence people and creatures, pathosystem hereditary qualities, and administration of plant ailments.

Plant diseases cause by fallowing factors

•       Abiotic factors: Environmental stresses i.e. High or low humidity, soil salinity, high or low temperature etc.)

•       Biotic diseases: Fungus, Bacteria, Virus ,viriods, mollicutes  Nematodes etc.

How Micro organisms act on plants

·         Cell wall-degrading enzymes: These enzymes  break down the plant cell wall in order to release the nutrients inside.

·         Toxins: These can be non-host-specific, which damage all plants, or host-specific, which cause damage only on a host plant.

·         Effector proteins: These can be secreted into the extracellular environment or directly into the host cell, often via the Type three secretion system. Some effectors are known to suppress host defense processes. This can include: reducing the plants internal signaling mechanisms or reduction of phytochemicals production. Bacteria, fungus and oomycetes are known for this function

Fungal Diseases

•       Damping off

Pythium, Phytophthora , Rhizoctonia

•       Anthracnose

Colletotrichum orbiculare & C. lagenarium

•       Downy mildew

Pseudoperonospora cubensis

•       Powdery mildew

Erysiphe cichoracearum

•       Wilt/Foot rot

 Fusarium oxysporum

Bacterial Diseases

•       Bacterial wilt

Erwinia tracheiphila

•       Angular leaf spot

Pseudomonas syringae

Viral diseases

•       Cucumber Mosaic Virus

•       Squash Mosaic Virus

•       Watermelon Mosaic Virus

•       Zucchini Yellow Mosaic Virus

•       Papaya Ring Spot Virus

Nematode Diseases

Root Knot Nematode(Meloidogyne incognita)

Damping off

Disease development factors

Disease favors warm, humid conditions

 Control Measures:

•       Soil solarization may be helpful

•       Sanitation, prompt removal of symptomatic plants

•       Seed treatment with Thiophenate methyl or Carbendazim @ 2 gm / Kg seed

Anthracnose

Leaf lesions are more or less circular and usually start near the veins

Picture shows leaves ranging from healthy (top left) to completely dead (lower right).

Severe leaf infection can result in loss of many leaves; a situation that decreases the photosynthetic activity of the plant

Infection points on the fruit are circular and sunken.  Internal infection discolors the fruit and makes it unsuitable for market

 Control Measures:

u Deep tillage immediately after harvest

u Plant only pathogen-free seed

u Crop rotation - At least 2 years between cucurbits

u Seed treatment with Thiophenate methyl or Carbendazim @ 2 gm / Kg Seed

u Spray with Topsin-M or Carbendazim @ 2.5 gm/lit. water

Downy mildew

•       Small yellow spots on the upper surface of older leaves.

•       Lesions expand and in time become necrotic

•       Yellow spots on the upper side of leaves

•       Fluffy purplish mildew on underside of leaves

 Control Measures

•       Avoid over irrigation

•       Avoid overcrowding of plantings

•       Crop rotation.

•       apply appropriate fungicide

•        

Product	Active ingredient	Dose/100 lit.water
Champion 77% WP	Copper Hydroxide	200 gm
Folio Gold 440 SC	Chlorothalonil	1000 ml
V-Nurse 70% WP	Fosetyl aluminium + Mancozeb	330 gm
Ridomil Gold 68% WG	Mefenoxam +Mancozeb	250 gm
Feast-M 72% WP	Metalaxyl+ Mancozeb	250 gm
Metacarb 25% WP	Metalaxyl + Propamocarb	330 gm
Proctor 25% EC	Difenoconazole	200 ml
T-Zole 25%	Tebuconazole	250 ml
Score 250 EC	Difenoconazole	200 ml

Powdery Mildew

•       Talcum like powdery growth on leaves, stems

•       Infected leaves and stems wither and die

Control Measures

•       Avoid crowding of plants

•       On the appearance of disease spray with

Product	Active ingredient	Dose/100 lit.water
Score 250 EC	Difenoconazole	200 ml
Contaf + 5.1% SC	Hexaconazole	200 ml

Wilt/Foot rot

•       Fungus enters plant through roots and causes rotting of seedling stems at soil line

•       brown lesions on one side of stem; discoloration of tissue inside vine

Control Measures

•       Crop rotation as long as possible between plantings for 4 to 8 years.

•       Soil solarization of the sick field.

•       Seed treatment with Thiophenate methyle or Carbendazim @ 2 gm / kg of seed.

•       Use of Trigopopak, Aspergopak along with wheat straw in the soil helpful in controlling the disease. 

Bacterial wilt

•       Slimy dull green patches on leaves and stems;

•       leaves appear dark green;

•       dark discoloration on leaves and stems;

•       Infected plants will ooze strings of bacterial exudate

•       rapid plant death

 Control Measures

•       Control cucumber beetle populations on plants;

     (hand pick adult beetles and destroy)

•       Soil and foliar application of appropriate insecticides may help to control populations

Angular Leaf Spot

•       Leaf lesions bounded by veins - angular appearance

•       Fruit lesions small, circular, water-soaked spots

•       internal rot of fruit

 Control Measures

u Rotate crops - 2 years minimum between cucurbit crops

u Irrigation to avoid prolonged wetting of foliage and fruit

u Season ending sanitation

u Spray with Streptomycin sulphate @ 1 to 2 gm/lit.water

Root Knot Nematode

Control Measures

•       Green house steaming

•       Application of Carbufuran @ 1.5 kg/ha. Below the seed level also reduces the attack of Meliodogyne incognita

Application of Pasteuria penetrans Very effective against  Vegetable Root knot Nematode