The preceding columns focused on the relevant aspects in the various stages of development of the determinate tomato plant: from seed extraction and sowing to germination, covering all the phases including flowering and fruiting, in which green, unripe tomatoes start to appear in clusters on the plant.

But instead of moving on to the phase when the eventual red tomato harvest begins — for which there are specific manoeuvres — we will address a very critical aspect of growing a determinate tomato plant: elements that are injurious to the plant and may cause stunting, diminished output, lower quality or, sometimes, even be fatal to determinate tomato plants.

These threats include common pests as well as infections and diseases that may affect the plant. However, there are remedies and probable prophylactic measures to not only counter these threats, but to stop them from occurring in the first place.

The protection of the plant begins from the sowing and seedling stages, such as the installation of green nets to shield the plant from birds and small animals. The threats continue to grow along with the plant and require mitigation during the maturity and harvesting phases too.

A successful determinate tomato harvest isn’t just about planting and watering, it’s about protecting the plant at every stage, from threats ranging from fungal infections and pests to nutrient deficiencies…

Powdery mildew, anthracnose leaf spot, sunscald, tomato blight, leaf mould, Septoria leaf spot and blossom-end rot are some of the common diseases, issues and fungal infections of the tomato plant at different stages.

Sunscald, as the name suggests, usually occurs in green, unripe to newly ripened tomatoes that may be exposed to excessive or scorching sunlight. The part of the tomato under the direct sunlight dries off, resulting in the skin texture of the tomato turning hard and papery. Instead of turning red, the hardened part turns to white to pale yellow in colour. This new discoloured patch also makes the tomato susceptible to different other bacterial and fungal infections, while also causing the tomato to decay and rot.

Therefore, it is recommended to remove the affected fruit immediately from the plant, as it will not heal. The use of a green net or any other cloth to cover and protect the plant from direct sunlight, along with pruning the plant in a manner to keep the branches covering the fruits within, can help safeguard the developing fruit from the scorching sunlight and the resulting sunscald in the first place.

Another very common issue, usually with unripe tomatoes, is a condition known as blossom-end rot. This disorder is manifested by brown or black spots occurring at the end of the tomato. It usually happens due to the deficiency of calcium availability to the fruit.

However, this deficiency of calcium seldom stems from the soil nutrient content. If so, the soil can be easily boosted with any of the commercially available calcium-based fertilisers especially prepared for tomato plant growth. Mostly, the soil content of the calcium is up to the mark. It is the transport of this calcium from the soil — through the roots, stems, branches and to the eventual fruit — using different absorption methods that is lacking.

Gardening basics, such as watering schedule and watering quantity, should be revisited to ensure that enough water is being made available to the plant to take all the nutrients, including calcium, from the soil to the fruit — and any watering anomalies should be addressed and corrected accordingly.

Dozens of pests, including but not limited to the likes of aphids, spider-mites, tomato russet mites, tomato fruit worm, tomato leafminer, leafhoppers, stink bugs, flea beetles and thrips, can be detrimental to the growing tomato plants at different stages of their plant life cycle. Most of these can be easily prevented with fortnightly sprays of organic pesticides.

One of the basic organic pesticides can be mixing a spoonful of neem [margosa] oil in one litre of water to prepare a spray for prophylactic purposes. In case of attacks of most of the above-mentioned pests, this pesticide-spray solution is boosted with the addition of a couple of drops of any dish-washing detergent being used at home. However, it is recommended to manually remove the pests and insects before spraying. This can be done using your fingers or a stick.

In case of infections caused by the likes of leafminers, the infected leaves have to be pruned before misting and drenching the plant with the protective pesticide spray.

Please send your queries and emails to doctree101@hotmail.com. The writer is a physician and a host for the YouTube channel ‘DocTree Gardening’ promoting organic kitchen gardening

Published in Dawn, EOS, March 16th, 2025