My bag is white, not green. Can I use it?

Ready culture is green spores covering the rice. White before day 5 means too much starter went in; past 15 days the culture grows white threads over the rice, which still works but is weaker. A bag with spots of another colour is contaminated with other organisms and should not be used.

Can I use Trichoderma together with PD.3 or a Bacillus product?

The Chonburi plant protection centre's manual advises against using Trichoderma together with Bacillus subtilis. PD.3 is a formula the Land Development Department has already combined, so use it as its sachet says, and do not mix separate products yourself.

My seedlings have already collapsed. Will Trichoderma save them?

Trichoderma reduces disease organisms in the soil and protects roots, so it works best when added before planting or at sowing. Seedlings already pinched and rotted at the base rarely recover; pull them out and treat the soil and the next sowing.

Trichoderma at home: the good fungus against damping-off and root rot

Trichoderma is a fungus found in almost every soil, but some strains are very good at dealing with the fungi that make seedlings collapse at the soil line (damping-off) and rot roots and stem bases, so agricultural agencies use it as a biocontrol product. It works in a home container garden too, as long as you remember one thing: it is alive, and direct sun and chemical fungicides kill it.

This lesson covers which diseases Trichoderma controls, how it works, how to grow it on cooked rice, and how much to mix into pots, following manuals from Thailand’s Department of Agricultural Extension and Rice Department.

What it controls

The manual from the Chonburi plant protection technology centre (Department of Agricultural Extension) lists these disease fungi that Trichoderma can control:

Disease organism	What you see in vegetables
Pythium	damping-off, seedling rot, root and stem-base rot
Rhizoctonia solani	seed rot, seedling blight
Phytophthora	root and stem-base rot
Sclerotium	stem-base rot, wilting
Fusarium	wilt

The Thai Innovation List entry for a T. asperellum strain registered with the Department of Agriculture names similar diseases and adds anthracnose in chilli. Commercial Trichoderma products are classed as Type 2 hazardous substances and must carry a registration number and label, so read the label of whatever you buy.

How it works

It is not a chemical; it is a fungus that fights bad fungi in the soil. The extension manual lists five mechanisms:

Competition. It grows fast, makes lots of spores and feeds on organic debris.
Parasitism. It coils around the disease fungus, releases enzymes that break down its walls, then grows inside it.
Inhibitory compounds such as antibiotics and enzymes.
Triggering resistance in the plant.
Healthier roots, by reducing microbes that bother them.

Because it has to grow and compete in the soil, it needs soil that is moist but not waterlogged, some organic matter, and it has to arrive there alive.

It is alive: what kills it

Direct sunlight. The Rice Department warns that bags must not sit in the sun while the culture grows, because sun kills the fungus. Spray in weak sun or in the evening.
Fungicides. The extension manual says never to use it together with carbendazim, difenoconazole, chlorothalonil or propiconazole, and never to apply a fungicide after applying Trichoderma.
Astringent plant ferments, which hold back its growth. Do not mix them.
Near mushroom growing. This one runs the other way: Trichoderma will eat the mushroom substrate, so keep it away.

Trichoderma is a living fungus. Direct sun kills it, and so does a fungicide applied with it or after it.

Growing Trichoderma on cooked rice, out of direct sun

Growing it on cooked rice

Rice Department and extension documents use the same method:

Cook 3 parts rice to 2 parts water, firm but done. Fluff it to let heat out.
Spoon 250 g into each clear heat-proof plastic bag, fold the top over, and let it cool to warm, about 20 minutes.
Add the starter (about 1 teaspoon of powder starter per bag in the Rice Department leaflet, or 3 drops of liquid starter per 250 g of rice in the Chonburi manual). Tie the band high and shake to spread it.
Prick 15-30 holes just below the band so air can get in.
Leave the bags in a bright, airy, shaded place out of direct sun, at around 25-30°C. After 1-2 days, knead the bag to break up the threads.
After about 7 days, green spores cover the rice throughout. It is ready.

While you work, do not put your hand inside the bag, turn off fans while you scoop rice and add starter, and do not talk over the open bag, so other organisms stay out.

Mixing it into pots and beds

The extension manual says to feed the fresh culture first, then use it on soil.

Step 1. 1 kg of fresh culture + 4 kg of fine rice bran + 100 kg of finished compost, mixed well.

Step 2. Use that mix by job:

Job	Rate of the mix
potting mix	1 part mix to 4 parts potting medium
seedling bed / broadcast on a bed	50-100 g per m²
planting hole / nursery bag	25-50 g per hole or bag
chilli, eggplant	50-100 g per plant

To water it in, use 1 kg of fresh culture per 200 litres of water: knead to wash the spores off the rice, strain out the grains, and pour 1 litre per m² of soil, or spray 1 litre over 5-10 m² of foliage. Watering the soil before or after spraying helps the fungus work. Use a mixed batch all at once.

Worked example: one bag of culture in a home garden

You have one 250 g bag of fresh culture and want to drench a bed and mix some potting soil.

Drench. 1 kg per 200 litres = 5 g per litre. A 10-litre watering can takes 5 × 10 = 50 g of culture and covers 10 m² at 1 litre per m². A 1 × 2 m bed uses only 2 litres.
Make the soil mix. Take another 50 g and keep the 1 : 4 : 100 ratio = 50 g culture + 200 g fine bran + 5 kg compost.
Fill a pot. For a 10-litre pot at 1 part mix to 4 parts medium = 2 litres of mix + 8 litres of potting medium.
That leaves 150 g of culture. Use it within a few days or refrigerate it, within the times below.

For a basic potting recipe, see mixing potting soil for vegetables.

Storing fresh culture

Fresh culture is best used straight away. The Chonburi manual says it keeps about 15 days in the shade out of the sun, and in the fridge about 1 month for cooked rice or 2-3 months for steamed rice. The Rice Department leaflet gives about 15 days in an ordinary fridge at 6-8°C. The figures differ with the method, so the shorter one is the safer one to go by.

Common mistakes

Leaving bags in the sun. The fungus dies. Bright shade only.
Following it with a fungicide. That kills what you just put in.
Adding it to dry soil. It needs moisture to grow and compete.
Forgetting to prick the bag. No air, no growth.
Expecting it to cure rotted plants. It works best as prevention, at sowing and soil preparation, and soil that stays soggy still needs better drainage; see the rainy-season garden.

Sources

General information, not medical advice. If you are pregnant, take regular medication, or have a liver or kidney condition, ask a doctor or pharmacist before taking herbs beyond normal food amounts.