After patiently tending to tomato plants for months and watching the green fruits develop, noticing the leaves inexplicably turning brown can be worrying. These troubling brown spots and streaks marring healthy foliage indicate stress. Let’s examine the common culprits behind this issue and best remedies.
Tomato Leaf Scorch
Leaf margins with yellow or brown patches is typically a case of leaf scorch in tomatoes. This arises from:
Insufficient Soil Moisture: Tomato plants need consistently moist soil as they possess shallow root systems. Sub-optimal watering causes dehydration affecting older leaves first. Deep water thoroughly without overwatering to hydrate plants and moisten surrounding soil too.
High Temperatures: Tomato foliage readily wilts and scorches when subjected to temperatures exceeding 85°F coupled with low soil moisture. Provide shade covers, mist plants, and avoid afternoon watering in extreme summer heat.
Wind or Air Pollution Damage: Strong winds and pollutants corrode leaf surfaces causing brown spotting. Shield plants with protective barriers and avoid planting along roadsides.
Sunscald: Younger top leaves that receive excess sunlight also display browned areas and curling. Light shade nets prevent sun damage while allowing airflow and moisture retention.
Once scorch symptoms manifest, prune back seriously affected leaves which hampers recovery. Adjust environmental conditions and culture practices as well to alleviate and prevent recurrence of damage.
See also : Why is my tomato plant not flowering ?
This potentially destructive fungal disease triggered by the pathogen Alternaria solani spreads fast under warm, humid conditions causing dark brown spots ringed by yellow halos on older bottom leaves that eventually kills them. As the fungus progresses upwards on the plant during favorable weather, it can swiftly destroy foliage and declining plants fail to set fruit.
To curb early blight infection:
Improve air circulation and reduce wetness around plants through proper spacing, staking and mulching
Avoid overhead watering and prolonged moisture on leaves
Apply copper-based fungicidal spray treatments after first symptoms appear
Remove and destroy severely infected leaves promptly
Grow blight-resistant tomato varieties in future
Septoria Leaf Spot
Another fungal disease producing small circular spots that first appear water-soaked then become brown. The centers break down and holes form as disease progresses killing affected leaves.
Amend these by:
Regular deep watering based on soil feel not schedule
Layering organic mulch over soil to retain moisture
Liming acid soils to keep calcium available
Sheltering plants under shade material during heat waves
Another foliar fungus causing yellow patches on upper leaf surfaces eventually becoming brown and fuzzy in very humid zones. As spores easily travel between plants, leaf mold spreads widely during favorable weather once established in the garden.
Alongside general sanitary practices, specific management strategies include:
Improve light exposure and airflow circulation around plants
Water soil directly avoiding wetting foliage
Remove infected leaves immediately upon noticing
Apply registered fungicides to protect new growth
Remove and destroy heavily infected plants
Serious Slip-ups to Avoid
Other easily avoidable but all too common mistakes that induce tomato leaf browning are:
Using lawn trimming remnants containing herbicide residue as mulch
Spraying plants with fertilizers or pesticides formulated for fruits and vegetables
Disturbing roots through shallow cultivation causing injury
The Bottom Line
If prized tomato plants begin showing leaves drying out and turning brown, don’t panic. Observe where damage started, how rapidly it’s increasing and the pattern formed. This provides vital clues to correctly diagnosing whether biotic stresses like fungal infections or abiotic factors such as moisture fluctuations are responsible. Consistent care tailored to symptoms allows still enjoying those vine-ripened tomatoes.