Monitoring of Crop Pests, Diseases and Weeds

Study the Pests, Diseases and Weeds

Regular monitoring of pests, diseases and weeds is the basis for effective management. To be able to manage pests, diseases and weeds, information is needed on the specific pests, diseases and weeds present in the region, village or crop fields and the associated damage they cause.

Typical signs of pest attacks on crop plants

Most crop pests belong to the insects, mites and nematodes. Pest damage is obvious and easy to identify.

Insect damage can be categorized by biting and chewing (e.g. caterpillars, weevils), piercing and sucking (e.g. aphids, psyllids) and boring (e.g. borer, leaf miner) species. Some are slow moving (e.g. caterpillars), fast moving (e.g. fruit flies), hidden (e.g. stem borer), or easy to observe (e.g. caterpillars, weevils).

Pest damage is often species-specific: leaves with holes or missing parts is an indication of caterpillar or weevil damage; curled leaves is an indication of aphids; damaged or rotten fruits are often caused by larvae of fruit flies; withering plants can also be caused by larvae of noctuids or the stem borer; and branches or trunks with holes may be an attack by lignivorous insects.

Mites are very small and cannot be seen with the naked eye. However, some mite species (spider mites) weave a typical tissue on attacked plant parts and can therefore, easily be detected. If mites are present on plants, leaves and fruits, become yellowish.

Nematodes are also very small and therefore, they are not easy to observe with the naked eye. They mostly attack plant roots; plants become yellow, wither and die.

Typical signs of disease attacks on crop plants

Most crop diseases are caused by fungi, bacteria or viruses.

Fungi cause the great majority, estimated at two-thirds, of infectious plant diseases. They include all white and true rusts, smuts, needle casts, leaf curls, mildew, sooty moulds and anthracnose. In addition, they are responsible for most leaf, fruit, and flower spots, cankers, blights, wilts, scabs, and root, stem, fruit, wood rots among many others. Parts of plants or the total crop plant can wither and die.

Bacteria cause any of the four following main problems. Some bacteria produce enzymes that breakdown the cell walls of plants anywhere in the plant. This causes parts of the plant to start rotting (known as ‘rot’). Some bacteria produce toxins that are generally damaging to plant tissues, usually causing early death of the plant. Others produce large amounts of very sticky sugars; as they travel through the plant, they block the narrow channels preventing water getting from the plant roots up to the shoots and leaves, again causing rapid death of the plant. Finally, other bacteria produce proteins that mimic plant hormones. These lead to overgrowth of plant tissue and form tumours.

Viruses mostly cause systemic diseases. Generally, leaves show chlorosis or change in colour of leaves and other green parts. Light green or yellow patches of various shades, shapes and sizes appear in affected leaves. These patches may form characteristic mosaic patterns, resulting in general reduction in growth and vigour of the plant.

If you enjoyed this post about crop scouting and would love to see more, join us on YouTube, Instagram, Facebook & X !

Growing Cabbage in Zimbabwe and Zambia

Growing cabbage in Zimbabwe and Zambia requires careful consideration of the climate and soil conditions, as well as proper planting and care techniques. This article provides a comprehensive guide on how to successfully grow cabbage in these regions. From the ideal temperature and soil pH requirements to pest and disease management, as well as harvesting and storage techniques, you will find all the information you need to cultivate healthy and abundant cabbage crops. Read on to discover the key takeaways from each section. Key Takeaways Understanding the ideal temperature and soil pH requirements is crucial for successful cabbage cultivation. Proper watering and irrigation techniques are essential for maintaining healthy cabbage plants. Choosing the right cabbage varieties for the specific region can significantly impact crop yield. Careful soil preparation, seed sowing, and transplanting techniques are important for successful cabbage planting. Effective pest and disease management ...

Staking and Pruning Tomatoes in the Home Garden

Staking and pruning tomatoes are essential practices for maintaining healthy tomato plants in the home garden. By selecting the right tomato varieties, preparing the garden properly, and employing the correct staking and pruning techniques, gardeners can ensure a bountiful harvest of delicious tomatoes. This article will provide key insights into staking and pruning tomatoes to help you achieve successful growth in your garden. Key Takeaways Select disease-resistant tomato varieties to prevent common plant diseases. Amend the soil with organic matter for optimal tomato growth and fruit production. Properly stake tomato plants to support their growth and prevent damage from heavy fruit loads. Regularly prune tomato plants to remove suckers and maintain airflow, which can improve fruit quality. Avoid over-pruning tomato plants as it can reduce yield and stress the plants. Selecting the Right Tomato Varieties Determining Your Growing Conditions ...

Chinese Cabbage Production

General Requirements Chinese does well in warm seasons of the year. Optimum temperatures for growing are 20ºC to 25ºC, with minimum temperatures of 18ºC and maximum 30ºC. A well-managed chinese crop should yield 5 tons per Lima with a leaf cutting period of 40 to 50 days. First leaves can be harvested 21 days after transplanting. Land Preparation/Soil Type Deep well-drained loamy soils with a pH range from 5.5 to 6.5 is ideal for Chinese cabbage. Effective rooting depth is 60cm. Plough and disc to a 60cm fine tilth seedbed. Avoid planting Chinese cabbage on land previously planted to other brassicas for at least one season. Planting and Transplanting Sow directly by drilling in the farrows 1 to 2cm deep or raise seedlings in nursery beds and transplant 4 to 5 weeks later. Transplant during the cool part of the day (early morning or late afternoon) to avoid wilting of the plants. Space the plants at 20cm between plants and 60cm between rows to give a plant population...

Zambia Agribusiness Society

Search This Blog