Causes of Yellowing Leaves in Watermelon Seedlings and Treatment Methods with Medication

When you are growing watermelons, do your healthy seedlings suddenly develop yellow leaves and wilt a little more each day? Don't worry - today we will talk about the causes of yellow leaves, because only by treating the right cause can you save them.

1. Herbicide damage

Did you accidentally spray herbicide on the seedlings? Or did spray drift from the neighboring field hit them? Seedlings damaged by herbicides suddenly turn yellow and curl, and in severe cases the leaves scorch outright! If you look closely, you can also find irregular yellow spots on the leaves, as if they had been scorched by fire.

Emergency treatment

Ventilate immediately: as soon as you notice something is wrong, ventilate right away! If you grow in a greenhouse, open all the roof vents and side vents; if you grow in the open field, do not cover with shade netting either - let the toxic gas disperse first, and ventilation should ideally last for 2-3 days.

Biological detoxification: drench the roots with a microbial inoculant! Bacillus subtilis or EM bacteria both work; dilute with water according to the product instructions and soak the root zone of the seedlings thoroughly. These beneficial bacteria not only break down toxins in the soil but also promote root growth.

Flood irrigation: finally, flush the soil with a heavy flood irrigation! This dilutes the pesticide residues in the soil, but do not let the seedlings sit in water for more than 6 hours, or the roots may suffocate. It is best to water slowly with a small amount, and drain promptly after watering thoroughly.

Once they recover, remember to spray some amino acid foliar fertilizer to replenish nutrients and grow new leaves! Spray once every 3-5 days, and 2-3 consecutive applications give a better result.

2. Root burn
 
Did you bury unfermented chicken manure or cow manure straight into the soil? Or spread too much chemical fertilizer? Seedlings with root burn have scorched leaf edges, and when you pull them up gently, the roots are dark brown and give off a foul, rotten smell!

Prevention methods:
 
1.Organic fertilizer must be fully composted! Chicken manure should be piled for at least 3-6 months, until it ferments to the point that it no longer feels hot to the touch, has no foul smell and has turned dark brown. You can add a fermentation inoculant when composting to speed up decomposition.

2.If you find root burn, do not hesitate! Immediately apply a microbial inoculant by flushing it on (per mu, 5-10 jin), then water thoroughly to dilute the fertilizer damage. If the root burn is severe, it is best to dig out the soil around the roots and replace part of it with new soil.

3. Nutrient deficiency

Calcium deficiency: leaves are wrinkled, leaf edges scorched, and growing points die.

Magnesium deficiency: yellowing between the veins.

Iron deficiency: new leaves turn white, while old leaves remain normal.

Fertilizing methods:

1.Before planting, apply a base fertilizer, adding 20kg of high-calcium potassium-magnesium fertilizer per mu to top up the trace elements. You can also add an appropriate amount of bio-organic fertilizer to improve soil structure.

2.If the leaves have already turned yellow, spray foliar fertilizer right away! Mix chelated calcium, magnesium, boron, zinc and iron together with brassinosteroid and spray, once a week for 1 time, for 3 weeks in a row. It is best to spray on a clear evening, for better absorption.

4. Spider mites

Are there dense tiny white dots on the leaves, with little red specks crawling on the underside? That is spider mites! They specialize in sucking the sap from leaves, and in severe cases the whole plant withers! If you look carefully, you can also find fine webbing on the leaves.

Pest control tips:

1.Pull up all the weeds around the watermelon field, and the cleared weeds must be taken out of the field and burned, not left in the soil.

2. 1.8%Abamectin (Chongmankexing)2000-fold solution, or 2% abamectin1500-fold solution, and focus on spraying the undersides of the leaves! Spray once every 5-7 days, for 2-3 consecutive applications.
 
Everyday prevention tips
 
1.Inspect at least 2-3 times a week, so problems are found and solved early;

2.Test the soil pH and nutrient content once before planting each year, and supplement whatever is lacking;

3.Fertilize scientifically according to the growth stages of watermelons, and do not apply too much nitrogen fertilizer;

4.After harvest, promptly clear away leftover plants and fallen leaves to reduce remaining pathogens and insect eggs.