Potato treatments, most common diseases and pests of this vegetable

potato solanum tuberosum

The potato (Solanum tuberosum) is a herbaceous plant of the Solanaceae family, has white or violet flowers and underground stems with round, oval or elongated tubers. The plant is cultivated for these tubers that are edible, rich in starch, reason why they are used as well as in food, but also as fodder. The potatoes originate from South America, from the Andes Mountains region. In the pre-Columbian period, in the areas where Chile, Peru, Ecuador and Colombia are found today, about 200 potato species were grown. After rice, wheat and corn, potatoes are the fourth energy source used nowadays in food. They are grown in over 120 countries and are consumed daily by more than one billion people. In 2007, the total harvest of potatoes was 300 million tons.

potato solanum tuberosum

Main diseases

Potato mild mosaic virus caused by Potato Virus X. The attack appears on the leaves as yellowish-green spots, alternating with the normal green of the leaf. In the case of a stronger attack, the leaves become deformed and wrinkled, dark spots and necrotic streaks appear on them, and those same spots and streaks can also appear on the petiole and stems of the plant.

potato solanum tuberosum mild mosaic virus

Prevention and control measures:

  • cultivation of resistant varieties, planting of resistant tubers;
  • removal of attacked plants from the crop;
  • avoid plant injury.

The Y potato mosaic caused by Potato Virus Y. This disease manifests itself on the leaves and the aerial strains. On the attacked parts of the plant, striations, streaks and necrotic spots appear. The leaves are withered and dry, starting at the base of the plant. They fall from the stalk, so the plants remain with just a few green leafs on the tip of the petiole.

potato solanum tuberosum Y mosaic

Prevention and control measures:

  • cultivation of resistant varieties, planting of resistant tubers;
  • removal of attacked plants from the crop;
  • avoid plant injury.

Blackleg (Soft rot) is caused by Erwinia carotovora pv. atroseptica. Plants from infected tubers remain small, with weak stems, and erected branches. Sick plants can easily be pulled out of the soil, they do not produce tubers, or if tubers exist, they are infected by the soft rot. Inside the affected tuber pink-violet lesions can be seen. At a more advanced stage of the infection, caverns filled with a bacterial mucilage are formed, which emanate an unpleasant odour, due to the pulp of the tuber that decomposes completely.

potato solanum tuberosum Blackleg

Prevention and control measures:

  • avoid sprinkler irrigation;
  • treatments immediately after the disease with Zeama bordeleza, Champ 77 WG, Aliette 80WG (2 kg / ha), Bravo 500 SC.

Potato cancer is produced by the Synchytrium endobioticum fungus. The disease manifests itself on the underground organs of the potato (tubers, stolons), with the exception of the roots and rarely at the base of the stem and on the basal leaves. The attacked organs develop small, whitish, soft tumours, which later develop into brown and spongy ones, growing on the entire surface of the tuber, causing it to rot.

potato solanum tuberosum cancer

Prevention and control measures:

  • cultivation of resistant varieties, planting of resistant tubers;
  • crop removal of attacked plants;

The late potato blight is produced by the fungus Phytophthora infestans. The blight manifests on all the organs of the plant. On the attacked leaves yellow spots appear, first small with a diffuse contour and they grow in number at the edge of the foliage. The spots gradually increase in size, become brown, then dark-brown and are surrounded by a yellow stripe with irregular and diffuse edges. On the lower side of the leaves, a fine, whitish fluff can be observed, in the area where the spots can be found. On the affected tuber, the blight manifests itself as brown, brown-grey or blue spots, causing dry lesions and affecting the quality of the tuber.

potato solanum tuberosum late blight

Prevention and control measures:

  • planting healthy tubers treated with the fungicide Prestige 290 FS;
  • avoid sprinkler irrigation;
  • gathering and destroying vegetal remains in the autumn;
  • treatments with Zeama bordeleza, Previcur Energy, Dithane M45, Electis 75 WG.

Dry potato rot caused by the Fusarium solani fungus. The attack is manifested on the tubers, where brown spots appear, causing the tissue to soften in those areas. The pulp of the tubers rots and becomes brown in colour, then dries and hardens. Gradually, the attacked potato wrinkles, decreases in volume, and the pulp turns into a hard, yet brittle mass, yellowish-white in colour.

potato solanum tuberosum dry rot

Prevention and control measures:

  • planting healthy tubers;
  • avoid sprinkler irrigation;
  • gathering and destroying vegetal remains in the autumn;
  • disinfection of 2% copper sulphate deposits.

The potato early blight produced by the Alternaria solani fungus, usually occurs during blooming. Dark lesions with yellow borders can form concentric rings and raised and sunken tissue on the potato leaves and stems. The initial lesions are circular and with time, they become angular. The attacked leaves wilt, deform and dry out, but will remain attached to the plant. The fungus can easily pass from the leaves to the tubers when these are harvested in a rainy period. The disease is favoured by wet and dry weather conditions or high humidity periods, as well as and leaves wetness.

potato solanum tuberosum early blight

Prevention and control measures:

  • storage of tubers in a cold environment;
  • planting of late varieties that are less susceptible to the disease;
  • reducing plant stress by adequate fertilization and irrigation;
  • the severity of follicular symptoms can be reduced by applying appropriate fungicides such as Ortiva or Score.

Main pests

Potato cyst nematodes are 1 mm long roundworms that live on the roots of plants from the Solanaceae family, such as potatoes and tomatoes. They can cause the slowing of the plant’s growth. After hatching from their eggs, the larvae invade the tips of the roots, establishing a feeding site, thus affecting the development of the plant. At very high population densities, grave root damage can occur.

potato solanum tuberosum cyst nematodes

  • treatments with Force 1.5 G (15 kg / ha);
  • cleaning the equipment used in infested soil;
  • using tubers and seeds not infested with PCN

Wireworms can be detected when digging around the stalk of the plant. The larva stage of this type of worm can last between 1 and 5 years, depending on the species. When the crop plants are standing, chemical control is almost impossible. The treatment needs to be applied before planting or the seeds can be treated before using them. It is advisable to rotate crops with non-specific host plants in order to prevent the development of wireworms.

potato solanum tuberosum wireworms

Colorado potato beetle cause foliage damage to the plant, and in some cases, if the infestation is severe, plants can become completely exfoliated. The beetle can attack the plant in all its stages, and it can be recognised as an adult by its black and yellow stripes, and in its larval stage, due to its bright red body and black head.
It can be controled with Decis 25 WG, Actara 25 WG, Calypso 480SC during vegetation, and before planting, the tubers can be treated with Prestige 290 FS (60 ml / kg).

potato solanum tuberosum colorado potato beetle

The black louse can be treated with Decis 2.5 (0.2 l / ha), Fastac 10 CE (0.10 l / ha) during the vegetation period.

Aphids are small insects found on the underside of leaves or on stems, usually green or yellow in colour. They may also be pink, brown, red or black, depending on the species and the host plant. These can cause yellow, distorted spots on leaves, or anaemic buds. Aphids secrete a sticky substance that contains sugar, and favours the appearance of rot on plants. They are the most harmful to potatoes because they are the main virus transmitters of viruses such as X or Y virus, which in turn can cause other potato diseases. If the population of aphids is limited to just a few leaves, only those leaves should be will be wiped off or shaken in order to remove the pests. If the infestation is very high, insecticides must be applied.
Aphids can be fought with treatments such as Actara 25 WG or Mospilan 20 SG during the vegetation period, and before planting the tubers, these can be treated with Prestige 290 FS (60 ml / kg).

potato solanum tuberosum aphids

Cicadas winter as an adult on plant debris, on the surface of the soil and have several generations per year. They are very active during July-August, and they act by poking and sucking the cell juice from various parts of the plant. As a result of the attack, small spots appear on the leaves, which slowly turn brown. The attacked tissues then become necrotic, and sometimes the leaves get twisted and no longer grow. Cicadas are very dangerous insects because they also transmit the mycoplasma bacteria that produces stolbur, another disease of the Solanaceae family.
They can be fought off with chemical treatments with one of the following products: Confidor Energy, Actara 25 WG, Mospilan 20 SG, Nurelle D.

potato solanum tuberosum cicadas

The potato flea beetle (Epitrix cucumeris) winters as an adult, and in favourable weather conditions, it can have up yo three generations per year. Adults appear early in the spring and produce damage to the foliage of the plant. They create a ‘shothole’ aspect on the potato leaves, by eating small parts of it, making young plants and seedlings particularly susceptible to an attack. They can slow the development of the plant, or even end up killing it, if the attack is severe. Larvae also affect the potato, as they develop in the soil and chew galleries in the tubers.
Chemical treatments can be done with the following products: Confidor Energy, Actara 25 WG, Mospilan 20 SG.

potato solanum tuberosum flea beetle

The cockchafer, also known as the May beetle (Melolontha melolontha) is a polyphagous specie and has one generation every 3-4 years. The larvae develop in the soil and attack the underground organs of the plants (roots, tubers, etc.), but the adults are not dangerous for the potato culture.
Control of this beetle can be done through chemical treatments with one of the following products: Karate Zeon 50 CS, Decis Mega 50 EW, Actara 25 WG, Confidor Energy, Fastac Active.

potato solanum tuberosum cockchafer

The potato Tuber moth (Phthorimaea operculella) appears in spring as an adult and lays eggs over the aerial parts of the plants, on the soil or on the vegetal remains on the ground. After hatching, larvae cause significant damage to the crop. Gnaw marks and galleries appear on the stems and leaves, and on the tubers, as larvae dig galleries that communicate with the outside of the plant.
Chemical treatments can be done with one of the following products: Decis Mega 50 EW, Laser 240 SC, Karate Zeon 50 CS, Kaiso Sorbie 5 WG.

potato solanum tuberosum tuber moth

The mole cricket (Gryllotalpa gryllotalpa) is a polyphagous species which attacks the underground organs of the plants. Roots are sliced, and in the tubers, the pest can produce galleries and gnaw marks, affecting the quality of the vegetable.
Control of the pest can be achieved with ground chemical treatments, by using Corocid Forte.

potato solanum tuberosum mole cricket

The turnip moth (Agrotis segetum) has two generations per year and winters as larvae of different ages in the soil. Adults are not dangerous to the plant, but larvae feed on all the parts of the plant. They prefer the tuber and stem regions, where they produce feeding cavities.
Chemical soil treatments can be done with: Kaiso Sorbie 5W, Mavrik 2F, Novadim Progress, Affirm, Confidor Energy.

potato solanum tuberosum turnip moth

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