Potato Care In The Second Half Of The Growing Season

2024 Author: Sebastian Paterson | [email protected]. Last modified: 2023-12-16 13:47

Read the previous part. ← Caring for potatoes in the first half of the growing season

How to save your potato crop

In the middle of the growing season (2-3 decade of July - beginning of August), active harvesting of early potato varieties takes place, especially if they were planted in the first decades of May with well vernalized material.

As a rule, tubers of these varieties are not left for storage (except for the seed fraction), but are consumed until winter. The harvest of plants, under which even single tubers with symptoms of soft rot are found during harvesting under the bushes, are realized in the first place, without leaving for seed purposes.

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Early harvesting of potatoes can avoid severe damage by late blight and serious damage by the Colorado potato beetle. Although meteorologists predict in the North-West region (with a probability of up to 70%) in July and August high temperatures, a shortage of precipitation, as well as a repetition of the pleasant wonderful weather of the first two decades of last year's September, one cannot exclude the possibility of a cyclone entering us and a malfunction due to this expected weather.

The summer will turn out to be dry and hot - the leafy part of potato plants will certainly be strongly affected by dry leaf spot (Alternaria), which appears on the foliage in the form of many concentric spots (the spot resembles a fingerprint). This fungal disease reduces the assimilation activity of the leaves, causes them to dry out prematurely and, as a result, a serious under-harvest and chopping of tubers.

The vegetation will be warm and rainy, the tops will be hit by late blight. The signs of this mycosis are the appearance of dark brown spots on the surface of the lower leaves of the plant, which quickly capture all of its aboveground mass. The causative agent of the disease is a parasitic fungus (it also affects the tomato 2-3 weeks after the appearance of the first signs on the tops of potatoes) forms a huge number of spores on the mycelium.

The widespread spread of infection is facilitated by warm weather during the day, when spores are blown off diseased leaves by ascending currents of warm air and are carried from garden to garden, causing the disease to spread quickly and widely around the area, especially if there are drops of dew or rain on the surface of healthy leaves. Moderately cool weather (10-20 ° C) and high air humidity also contribute to mass germination of spores. Late blight destroys not only the tops of plants.

Spores are washed off by dew or rain from diseased leaves, fall to the surface of the earth and, with the help of soil moisture, penetrate to the tubers, infecting them. The total crop losses from this disease are much greater than the damage from any other disease or pest. Plants are especially affected in those areas where varieties susceptible to late blight are planted and no chemical protection of the tops is carried out.

When 75% of the land mass of plants is affected by this disease, the increase in yield stops, i.e. the formation of new tubers and the growth of already established nodules. Yield losses as a result of premature death of foliage reach 50% and more.

To combat fungal diseases of potatoes, plant tops are sprayed with solutions of fungicides. It is often recommended that the first treatment be carried out at the first appearance of symptoms of the disease, the second - after 10-15 days or at the first manifestations of the disease (the third and fourth - as needed) with an interval of 10-15 days. But fungicides only protect against infection, but do not cure potatoes from diseases.

It is recommended to process healthy plants until they are infected. Therefore, it is still more advisable for the gardener to carry out preventive treatment of the bushes at the beginning of budding, without waiting for the first signs of late blight or macrosporiosis. Spraying heavily affected plantings seems to be a useless exercise. If the infection of plants with a pathogen has already occurred, then the process of development of the disease can only be slowed down, but it is no longer possible to completely protect the plantings from this scourge.

To protect against diseases, copper-containing preparations (for example, Bordeaux mixture is the oldest and most tested) and other recommended fungicides that will reduce the effect of pathogens of these diseases are suitable. Let me remind you how to properly prepare an aqueous solution of a 1% Bordeaux mixture, consisting of dry powders - copper sulfate (copper sulfate) and lime (calcium hydroxide). Use a wooden, glass or clay container (you cannot take metal containers). Copper sulfate is dissolved in a small volume of hot water (not higher than 50 ° C), then the total volume of the solution is brought to the recommended level. Lime is prepared in a separate container, adding it to water in small portions (until a creamy mass is obtained).

A solution of copper sulfate is slowly, with constant stirring, poured in a thin stream into pre-filtered milk of lime, but not vice versa (both solutions must be cold before joining). Before processing, the reaction of the Bordeaux mixture is determined using blue litmus paper or pure iron wire or a nail (for 1-1.5 minutes). If an iron object is covered with a red coating of copper (copper precipitates), then the reaction is acidic and milk of lime should be added to the solution.

Before pouring into the sprayer, the resulting solution should be filtered. Bordeaux mixture is prepared immediately before use (it is stored for no more than a day, as it ages, and the components of the solution precipitate). Soap should not be added to the Bordeaux liquid, as this cannot improve the wettability of the leaf surface. Bordeaux liquid is not used together with other drugs, since it is incompatible with them.

Copper chloroxide, SP (or Apiga-peak, VS, Copper oxychloride, SP) or Kuproksat, KS spray potato plantings with 0.4% (40 g per 10 l) or 0.25-0.5% working solution respectively. Oxyhom, SP is a complex of copper oxychloride and oxadixyl (5: 1); this mixed fungicide has a protective and curative effect. On an area of 100 m2, it needs 10 liters at 0.2% concentration with an interval of 10-14 days. In my opinion, in comparison with the listed preparations, the Bordeaux mixture is still "softer".

Another misfortune for our potato grower was the Colorado potato beetle, which can also damage tomatoes, eggplants and other nightshade crops. Now every gardener will distinguish the beetle itself and its voracious larvae from other insects. Recall that the emergence of adults on the soil surface from wintering usually occurs in late May - early June (this is facilitated by good soil moisture, especially warm rains).

The appearance of most of the overwintered beetles (up to 75%) is extended - from 3 weeks to 2 months. In search of food, they are able to fly, possibly drifting by air currents far from their wintering grounds. The female lays on the lower part of young leaves usually up to 500-600 eggs in groups (20-25 pcs.), Of which larvae hatch in a week, developing 3-4 weeks. The larvae have 4 instars (in the 1st - gray, in the 2nd - red, 3rd and 4th - orange). Caterpillars eat potato leaves, starting from the top, leaving only the stems.

Having destroyed the tops of one bush, they crawl to the next plant. The larvae pupate in the soil, and after 7-12 days young beetles appear. Larvae of 4 instars and young winged beetles are most voracious during the period of their fatty feeding. In cold (matinees) or hot weather, the beetle buries a few centimeters in the soil or hides under the tops.

In the fight against the Colorado potato beetle, the use of folk remedies is usually ineffective, and the use of biological drugs (bitoxibacillin, etc.) requires at least 5-6 treatments.

If they do not do the laborious daily manual collection of the pest and egg-laying, then they resort to spraying with solutions of chemicals that are more effective. In my opinion, in terms of effectiveness, these drugs can be arranged (as their action intensifies) in the following order: Intavir (represents only 3.75% of the active substance + 70% of urea + filler), Decis, Karate, Arrivo (Tsimbush, Sherpa, Tsitkor), Bankol, Regent, Spark, Fury, Sumi-alpha. Spraying should be carried out with the predominance of larvae of 1-2 instars on the plants (they are most sensitive to pesticides and biological products, since they have a soft cover that allows drug solutions to pass through well) with their mass appearance, the 4th instar is more stable. Processing is carried out in the afternoon.

When treating, a good sprayer should be used, which gives a sufficiently good spraying of the drug solutions and their application to the leaf surface of the plants.

When processing, you do not need to get carried away with an increase in the consumption rate of drugs and increase the concentration of solutions more than recommended in the instructions. In addition, the timing of the last processing before the expected harvest should be strictly adhered to. All precautions recommended when working with pesticides must also be followed.

Plants of vegetable and berry crops bordering on the plantings of solanaceous plants are covered with plastic wrap for the duration of processing, since the processing is carried out already during the period of pouring berries and fruits.

A good increase in the yield of tubers is provided by foliar feeding of the ground mass of plants during the budding period with a solution of a complex solution of trace elements (copper, manganese and zinc sulfates, 10 g per 10 liters of water and at a consumption rate of 1 l / 10 sq. M.), In addition to increasing the yield to 30- 50%, it also contributes to an increase in dry matter and starch content in tubers.

To increase the ground mass of plants, good results are obtained by spraying it with a fermented manure infusion, which I often practice on my plantings.