Potato insects, Pests ,Diseases and their management

Ø  Potato is the largest produced and consumed vegetable.

Ø  Pakistan is self-sufficient in potatoes for household consumption

Ø  relies for more than 99 per cent on locally produced seed potatoes.

Ø  the area under potato production has increased to around 1,07,000 hectare with the average yield rising from around nine to 20 tons per hectare.

Ø  Potato is the largest produced and consumed vegetable.

Ø  Pakistan is self-sufficient in potatoes for household consumption

Ø  relies for more than 99 per cent on locally produced seed potatoes.

Ø  the area under potato production has increased to around 1,07,000 hectare with the average yield rising from around nine to 20 tons per hectare.

Ø  popular varieties are Desiree (55.2%), Diamond (43.8%), Santhay (33.3%) and Cardinal (33.3%). Raja is also expanding its area.

Ø  Several countries in fact have witnessed remarkable acceleration in recent years. These include China with a 6.2% average annual rate of growth, Indonesia 10.6%; Nepal 8.8%. India and Pakistan saw their growth rates decline but they were still impressive at 4.6% and 6.0%, respectively.

Ø  Potato crop has a higher cost of production as compared to other crops, which is mainly due to high cost of seed that contributes 35-45 percent of the total cost of production and continuous usage of the broad spectrum insecticides.

Ø  Farmers, on average, applied 4.3 sprays for pest control. 
Seed treatment and roughing are important practices for quality seed production,

Ø  More than 80 percent farmers do not maintain isolation of seed potato fields and more than 70 percent do not care for roughing.  

Ø  A large number of farmers lack knowledge about cultivation technologies. These include pests and disease control, land preparation and irrigation, fertilizer application, crop rotation and multi-cropping pattern.

Soil Insects

Tobacco Wireworm

White Grubs

Soil insects, primarily wireworms and white grubs, can severely damage seed pieces and tubers. These insects feed on grass roots and should be considered as a serious threat when potatoes are to be grown in ground immediately following sod.

Green peach aphid

Myzus persicae (Sulzer), Aphididae: HOMOPTERA

Ø  Remove plant sap causing severely

     dwarfing and curling of the leaflets

Ø    Vector of several viruses

Ø    Potato virus Y (PVY)

      potato leafroll virus (PLRV).

Ø    Yield loses can be as high as 90%

Biological Control Agents

Ø   Aphidius matricariae

Ø  Other parasitoids Paron, Diaeretiella, Epherdus

Ø  Coccinellidae

     Chemicals

Ø  Pesticides used against      sucking insect as Bifenthrin and granular insecticides

Potato Leafhopper
Empoasca fabae (Harris) Cicadellidae: HEMIPTERA

Ø  triangular brown spot at the tip of

     the leaf.

Ø    Similar triangles appear at the end

     of each lateral veinlet

Ø   entire margin may roll upward as

     known as "hopperburn".

Biocontrol Agents

Ø  Coccinella septempunctata

Ø  Anagrus empoascae

Ø  Anagrus flaveolus

Ø  Anagrus giraulti

Ø  Arescon enocki

Ø  Stethynium empoascae

     Chemicals

Ø  Cypermethrin+hyghcis+
monocrotophos (Fenom-N 425 EC)

Ø  Cypermethrin+ profenofos (Polytrin-C 400)EC

Ø  Dichlorvos (Nokovos 100 EC, Fatek/DDVP 50EC)

Ø  Phosphamidon (Phosphamidon 100)

Sweetpotato whitefly
Bemisia tabaci Bellows & Perring, Aleyrodidae: HEMIPTERA

Cosmopolitan insect wide host range recorded on 500 host plants

Ø    Important pest of potato

Ø    Suck sap from leaves, turns  yellow

Ø    Source of virus transmission

Biocontrol agents

Ø  Eretmocerus spp

Ø  Encarsia spp.

Ø  Serangium spp

     Chemical Control

Ø  Dichlorvos (Nokovos 100 EC, Fatek /DDVP 50EC)

American bollworm Heliothis spp. LEPIDOPTERA

Ø  Attack on both autumn and spring season crop

Ø  Leaf feeding caterpillar

     which also bores into buds and tubers.

Biocontrol Agents

Ø  Microplitis demolitor

Ø  Cotesia spp

Ø  Corcyra spp.

Ø  Trichogramma spp.

Ø  Chrysoperla spp.

     Chemical Control

Ø  Endosulfan

Ø  Azinphos Methyl

Ø  Monocroto-phos (Nuvacron 40 WSC )

Ø  Bacillus thuringensis (Agree 0.6 WP)

Army worm
Spodoptera exigua (Hübner), Noctuidae : LEPIDOPTERA

Ø  Feeds on leaves, tender stems, and tips of branches

Ø  Congregates round bases of plants.

Ø  Young larvae feed gregariously and skeletonize foliage.

Ø  As mature, larvae become solitary and eat large irregular holes in foliage.

Biocontrol Agents

Ø  Orius tristicolor

Ø  Lygus hesperus

Ø  Hippodamia convergens

Ø  Chrysoperla carnea

Ø  Ophion bilineatus

Ø  Chelonus texanus

Ø  tachinid flies Winthemia quadripustulata

     Chemical Control

Ø  Ace hate (Orthene 75 SP)

Colorado potato beetle 
Leptinotarsa decemlineata (Say), Chrysomelidae: COLEOPTERA

Ø  Tomato, potato, tobacco, cherry  

Ø    overwinter in the soil as adults

Ø    become active again in the spring  and feed on weeds and volunteer on early planted potatoes.

Ø    enter the soil to attack emerging foliage

Biocontrol Agents

Ø  Myiopharus doryphorae

Ø  Edovum puttleri

Ø  Big eyed bugs, lacewings,

Ø  Coleomegilla maculata

      Chemicals

Ø  Chemical control is directed towards the first generation as subsequent generations may cause sever damage and defoliation

Pathogens and Diseases

Potato Late blight
 (Phytophthora infestans)

Ø  small, light to dark green,circular to irregular-shaped water soaked spots, appear first on the lower leaves.

Ø  cool, moist weather, these lesions turns into large, dark brown or black lesions,often appearing greasy .

Ø  tubers characterized by irregularly shaped, slightly depressed areas of brown to purplish color of variable size on the skin.

Ø  Severely infected tubers may display extensive rot.

Early Blight
(Alternaria solani)

Ø  Small, irregular, dark brown to black spots on older leaflets on lower portions of plants.

Ø  Large spots limited by large leaf veins.

Ø  A narrow light green to yellow halo frequently surrounds the spot.

Rhizoctonia stem and stolon Canker of Potato
(Rhizoctonia solani)

Ø  Dry, sunken, brownish lesions develop on the base of the stem below the soil

Ø  vines become yellow to reddish purple; the leaves begin to curl upward; the stalks swell at the nodes; often small purplish tubers form.

Ø  lead to surface cracking of mature tubers and sometimes shallow, brown lesions will form around lenticles.

Fusarium wilt 

(Fusarium spp.)

Ø  slight vein clearing on outer leaflets and drooping of leaf petioles.

Ø  later the lower leaves wilt, turn yellow and die

Ø  When stem is cut, dark, chocolate-brown streaks seen running lengthwise through the stem

Ø  wilting of the entire plant soon follows.

Verticillium wilt

Ø  Similar to those of Fusarium wilt

Ø  bottom leaves become pale, then tips and edges die and leaves finally die and drop off.

Ø  V-shaped lesions at leaf tips are typical of Verticillium wilt of tomato.

Ø  A light tan discoloration in the stem, confined to lower plant parts.

Ø  Tubers from Verticillium-infected plants may show light brown vascular discoloration, usually restricted to the stem end

Control

•         Grow resistant varieties

•         Where blight is common, grow early bulking varieties that produce a reasonable crop before blight appears.

•         Earth up or mulch with a thick layer of leaves, straw or hay, to reduce tuber infection.

•         Once the disease has taken hold it cannot be cured. To save the crop cut off and remove all foliage. Wait three weeks before lifting the tubers so any lingering spores, that could infect the tubers as they are lifted, will have died.

•         Water, if conditions are dry.