The spinach crown mite (Schizotetranychus celarius) is a tiny, almost transparent mite that can cause significant damage to spinach crops. It is most commonly found in soils high in organic matter and under cool, moist conditions. These conditions provide an ideal environment for the mites to proliferate and feed on the newly expanding leaves at the heart of the plant.
Crown mites are difficult to control because they can survive in soils after removing the crop and consuming organic matter to sustain themselves. This makes it challenging to eradicate them from the field, even using pesticides or other control methods.
Management of Crown Mite in Spinach
The Life Cycle of Crown Mite
- Egg stage: The transparent, spherical eggs are laid in the innermost parts of the plant. The eggs hatch in 2-4 days, depending on the temperature.
- Larva stage: The newly hatched larvae have six legs and are translucent. They feed on plant tissue and molt to the next stage after 1-2 days.
- Protonymph stage: The protonymphs are similar in appearance to the adults but smaller in size. They have eight legs and feed on plant tissue. They molt to the next stage after 1-2 days.
- Deutonymph stage: The deutonymphs are similar in appearance to the adults but still smaller in size. They have eight legs and continue to feed on plant tissue. They molt to the adult stage after 1-2 days.
- Adult stage: The adult crown mites are small, nearly transparent, with noticeable long hairs. Both the soil and the crowns of vulnerable plants contain them. They deposit eggs on the new growth and reside deep within the spinach plant’s crown. Throughout their existence, which can be as little as ten days in warm climates, the females can deposit up to 60 eggs. The full life cycle from egg to adult can be completed in as little as 5-7 days in warm conditions, causing rapid population expansion and crop infestation.
Identification of Crown Mite in Spinach Field
- Look for symptoms of crown mite infestation: The symptoms of crown mite infestation include stunted growth, yellowing of leaves, distorted growth, and reduced yield.
- Inspect the innermost parts of the plant: Crown mite eggs are transparent and spherical, laid in the plant’s innermost parts. Inspect the plant’s crown and the stem’s base to see if any eggs are present.
- Look for adult mites: Adult mites are tiny, almost transparent, and have prominent long hairs. They can be found in the soil and susceptible plants’ crowns.
- Look for protonymphs: Protonymphs are immature mites similar to adults but smaller.
- Check for mite movement: Use a magnifying glass to observe the movement of the mites. Crown mites are slow-moving and tend to stay in one place.
Damage Symptoms of Crown Mite in Spinach field
- Damage to seeds and seedlings: Crown mites can damage sprouting seeds and seedlings before or after emergence. The damage may include stunted growth, distorted leaves, and reduced seedling vigor.
- Damage to newly expanding leaves: Crown mites feed primarily on newly expanding leaves at the heart of the plant, causing damage that appears as deformed leaves or small holes in expanding leaves.
- Vector for plant pathogens: Crown mites can act as a vector for plant pathogens such as Pythium sp and Rhizoctonia sp, which can cause additional damage to the plant.
Management of Crown Mite in Spinach by Cultural Method
- Crop rotation