Bacterias: invisible diseases of the cucumber crop prevented with trellis netting

Tutoring cucumbers is a way to reduce diseases and provides conditions that reduce the incidence and development of bacteria.

It is very important to recognize cucumber diseases as soon as symptoms appear,  and know their possible treatments to avoid further propagation, increasing the effects of losses or affections they may provoke.

A lot of research went into knowing more about these diseases, and has turned into treatments that allow crops to develop without being attacked by pathogens. These treatments are more efficient if they are used in preventive ways, and it has been observed that their efficiency decreases once the crop is affected by the condition.

Better results are achieved when preventive measures are used along with sound cultural practices. Tutoring is an essential horticultural practice for growing cucumber.  A crop with a tutoring net like suggested by HORTOMALLAS, besides becoming more efficient when applying preventive chemical treatments, it will allows the plant to expand its sun light exposition and capture, while at the same time favoring aeration in between plants, avoiding excessive humidity accumulation that will encourage the development of diseases.

Angular leaf stain (pseudomonas syringae, P. Lachymans)

Angular leaf spot lesions on cucumber leaf
Angular leaf spot lesions on cucumber leaf

The pathogens responsible for this infection are the cucumber bacterias Pseudomonas lachrymans and P. Syringae.

Damages caused by these bacterias are observed on the leaf: on the top it shows points of humidity and on the lower part of the leaf we may see gray colored stains with a watery semblance sometimes delimited with a yellow halo.

Sometimes depending on conditions drops of exudate are present.

The leaf´s rib limits the stains which makes them have an angular shape. This pathogen may dry and fall from the rest of the leaf causing perforations.

Damages that may appear on the fruit are superficial and only skin deep, causing the fruit to have a poor aspect and affecting its marketable opportunity.

Bacteria is disseminated by rain or workers´ contact.

It is also transmitted by infected seeds.

(xanthomonas campestris pv cucurbitae )

bacterial diseases
injuries caused by cucumber bacteria stain.

Symptoms for this disease are similar to the angular stain, but bacterial stain does not show exudate drops, like angular stain this may infect stem, petiole and fruit. It presents humid stains that evolve to dry stains.

Bacteria rot or soft rot (erwinia carotovora)

cucumber affected by soft rot.
cucumber fruit affected by soft rot.

This bacteria is found in the soil.  In order to infect the plant it will use any vegetable matter wounds at the neck level, causing soft rot on the stem, tissues will assume a brown color and possible further stains will present depending on conditions.

When the bacterial infection is initiated, the fruit will appear as damp in certain areas that will rot later.

Bacterial diseases Agro-Chemical treatments

Usually all bacterial contagions are caused by: using infected seeds, bacteria use seeds as a way to disseminate, or direct mechanical contact with a sick plant, usually workers come in contact with plants during pruning during the right moon phase and tutoring.  Also insects may be the cause of mechanical transmission of bacteria in cucumbers.

If a plant is infected a diagnosis has to be done to know the type of infection we are dealing with.  Knowing exactly the type of pathogens we are facing with will increase the chances of a cure, by aiming specific targets.

Once we have the right diagnosis for cucumber disease we must apply the right treatment, but in most cases is recommended to erradicate the infected plants since most existing treatments are more useful in disease prevention.

The following agrochemicals can be used to prevent bacteria incidence in cucumbers: copper sulfate, copper hydroxide, copper oxychloryde, kasugamicina, streptomycin sulfate and oxytetracycline.

Bacterial withering, bacterial wilt (Erwinia tracheiphila)

bacterial withering on cucumber
Example of bacterial withering on cucumber.

This bacteria is transmitted by vectors like the beetles Acalymma vittata and Diabrotica undecimpunctata.

The first symptom observed in the plant affected by bacterial wilt is the sudden leaf withering that will later lead to plant´s death.

Since the infection of the crop is due to mechanical vectors, one of the preventive treatment is to avoid this vectors from entering the cultivated area or using insecticide to avoid beetles contact with the plant. (or better yet biological controls with the predator that feeds on these beetles.

Preventive measures to minimize bacterial infections:

recommendations to avoid bacteria incidence on crops are:

  • get the ground, tools and workers perfectly disinfected
  • using healthy seeds
  • monitoring the crop regularly
  • take away identified sick plant remains
  • eliminate possible reservoirs of possible vectors
  • crop rotation
  • eliminate undergrowth weeds
  • using bacteria resistant varieties
  • using trellises to avoid humidity accumulation

Cucumber plants with trellis net

Tutoring cucumber plants
Tutoring cucumber plants using vertical trellising net

The cucurbit netting by  HORTOMALLAS is recommended as preventive measure since it helps avoiding large periods of  humidity, and allows the crops better aeration; it reduces possible contagion by workers´s coming in contact with the plant as the netting requires a lot less labor than tutoring with raffia twine.

This informative material may be of help to identify bacterial diseases, but it is recommended to consult with your local trained agronomist for a better diagnosis and tests before deciding what course of action to take in order to save your diseased cucumber crop.

Trellis net
Trellis net usage is important for vegetable cultivating.

Biol. Diana Jiménez.

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