How to Collect a Sample for Pathological Analysis

Plant Pathology


We carry out plant disease diagnostics for commercial growers and small holder farmers. Rapid and accurate diagnosis of disease is always necessary before proper control measures can be suggested. Practical and experienced recommendations are given with each report

These services include investigations of plants, leaves, roots, soils, water and substrates for routine crop disease diagnosis, including common fungi and bacteria, such as leaf spots, root rot diseases, cankers and wilt diseases.

Our services give you the information you need to make the right decisions, ensuring you apply the correct product, quickly and effectively. Our services save you money.

We also provide virus detection using rapid field test diagnostic kits from Bioreba - for more information email

How to collect a sample for pathological analysis


Plant and soil sampling can either be done for diagnostic (problem/diseased) or predictive (routine) purposes. Proper sampling is critical as it will affect the results and therefore the decisions made. This

Scope: This documents outlines procedures to use while collecting samples for fungal and bacteria analysis.


1.                 Sample bags(we can supply at no charge)

2.                 Auger or shovel

3.                 Bucket

4.                 Sample submission forms (please request these from us)

5.                 Field logbook

6.                 Labels and marker pens

Diagnostic plant samples

These are taken when the plants have obvious symptoms.  The symptoms expressed are defined by the pathogen in question. Different plant parts will be affected / attacked . The grower should be able to distinguish a healthy plant from a "sick" plant for the correct sample to be collected. The common disease symptoms include; Wilting, stunting, leaf spots, cankers, rots and many more. Where the whole plant is not affected e.g. leaf spots, only the affected plant parts are collected. In case of a plant wilt, then its recommended the whole plant ( smaller plants) should be sampled. In case of trees, the lower portion should be sampled. Roots from the affected plants will also be ideal for the large trees.

Where a whole plant is sampled in cases of wilting;

Select plants that are partially wilted, with symptomatic leaves progressing from the tip of branches inward to the stem.

Carefully dig up the whole plant, including the roots and soil surrounding the roots.  Place the root ball and the soil in a large water proof bag.  Tie the top of the bag around the stem of the plant, to keep the root and soil intact and deliver as soon as possible to the laboratory. The samples should be delivered to the laboratory as soon as possible to avoid deterioration. Keep samples cool during sampling, shipping and storage, but do not freeze.

While sampling different crops / symptomatic plants, follow these procedures;

Herbaceous Plants

If possible, send entire plants including roots and some soil. Roots and soil should be in a plastic bag tied off at the soil line to prevent soil from touching foliage.


Leave the plugs in the tray for shipping purposes. A section of the tray can be cut and shipped. Submit a minimum of 12 plugs. Wrap the plug sheet in newspaper or add packing material that will prevent plugs from being dislodged from the tray.

Leaf Spots Samples

Select affected foliage, but if possible leave it attached to the branch. Send several affected leaves representing the early and moderate stages of symptom progression. Package in an envelope and ship in a box. This protects the sample during the shipping process.


These samples include plants, fruit, or both. If fruit rot is a concern select fruit that is in the initial stages of symptom development. Be sure to package in leak proof containers (sealable plastic bags).

Residential Turf

Include a square of turf from the margin of the diseased area so that both healthy and diseased turf is included. Minimally, the turf square should be 6 inches x 6 inches. An intact layer of soil should remain on the root system. Wrap samples in newspaper and pack in a box for shipment. Do not add moisture to the turf prior to shipment.

NOTE : If possible; provide a detailed description of cultural practices (irrigation, fertilization, pesticide application, etc.), disease development and distribution and images of the symptoms.

Types of sampling for disease diagnostics

Diagnostic: These samples are taken when plant growth is not satisfactory and the farmer suspects a disease problem.

Where to sample

Sample in locations in which plants are not growing properly (considering: weather, soil fertility, and other conditions).  Remember to take samples from good areas for comparison purposes.


These are taken if the grower is interested in knowing the status of the soil prior to planting so that necessary precautionary measures are taken. 

How to sample (Soil)

Whenever possible, collect soil from the root zone (10-15 cm depth) of growing plants, where disease spores will be concentrated, and include some root matter. The general sampling patterns are as shown below. At each sampling point, scrape off the top 3 cm of soil.

  •         Left: Star pattern for sampling from a damaged area.
  •         Center: circle pattern for sampling a shrub in an orchard.
  • Right: Zig-zag pattern for sampling a fallow field or one with no obvious disease symptoms.

Soil sampling for disease diagnostics

Please Note

Samples for pathological  analysis must be handled carefully, collected in bags which will not allow any cross contamination, kept moist, stored in a cool dry place out of direct sunlight and reach the laboratory as soon as possible, preferably at the beginning of the working week. The samples should be well labelled for faster processing.

Provide the same names used in previous sampling area to be able to have historical data.

For more information please contact us through:

Crop Nutrition Laboratory Services Ltd.

Off Limuru Road, Limuru, Kenya

Telephone +254 (0) 711094444, + 254 (0) 720 839 933


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