Powdery mildew is one of the most common problems to occur in a small garden. Balconies, patios and small footprint gardens where there is a high density of plants are more likely to have plants impacted by powdery mildew as there is often less sunlight, space and air-flow. Preventing powdery mildew is far more effective than treating it once it sets in. You can prevent powdery mildew by carefully utilising the space in your balcony or small space garden.
What is powdery mildew?
Powdery mildew is a fungus commonly found growing in the garden. It grows from spores that may lay dormant in the soil until the conditions are right to start growing. It typically appears as the weather warms but the evenings remain cool. It can begin as a mild dusting of white dots appearing like powder on the leaves of affected plants and can spread so the entire plant is covered with it.
Why is powdery mildew a problem
Powdery mildew does not penetrate plant leaves however it inhibits the ability of a plant to photosynthesise. Photosynthesis is essential for your plants survival as it is how your plant transform light from the sun into energy. During photosynthesis, plants use light to convert water, carbon dioxide and minerals into oxygen that is released into the air. Ultimately, left untreated, leaves of plants affected by powdery mildew will whither, brown and die back and the plant is likely to die. Powdery mildew is also likely to spread from plant to plant.
What causes powdery mildew?
By managing the growing conditions you can prevent powdery mildew organically. The following factors contribute to the growth of powdery mildew, particularly in a small garden like a balcony or patio area:
- High density plant environments mean air flow can be tight, increasing the chances of powdery mildew.
- Often poor light for instance from a roof or awning, can increase the growth of the spores causing powdery mildew.
- Planting plants that like full sun in too much shade can predispose those plants to powdery mildew.
- Watering in the afternoon, evening or night so the ground doesn’t have a proper chance to dry out.
- Foliage getting wet during watering from splashing or being directly watered.
- Spores spreading from old and diseased leaves.
How to prevent powdery mildew in a small garden
Once powdery mildew sets in, it can be difficult to completely eradicate. There are preventative strategies you can do to minimise the chances of it occurring in the first place such as:
- Plant plants with adequate space between them. In a balcony setting, it’s great to use vertical garden growing strategies like, Hanging pots which have plenty of ventilation and often great drainage, Grow walls and Tower gardens. You can increase the footprint of your small space garden by utilising these creative planting opportunities.
- Water in the morning, allowing the ground to dry out as much as possible throughout the day.
- Do not plant powdery mildew susceptible plants that like the sun, in shade areas. Plants like tomatoes and cucurbits including watermelons, cucumber, rockmelon, zucchinis and pumpkins are particularly prone to powdery mildew and do not fare well in the shade.
- Install a Balcony Balcony drip irrigation set directly on the ground so that there is minimal or no splashback of water on to plants. Shower watering from higher up increases the humidity in the area and increases the chances of powdery mildew spores propagating and spreading.
- You can use a small amount of bicarbonate soda diluted with water in a milky solution to prevent powdery mildew.
- Practice crop rotation on an annual basis so if there are spores in the soil, they are less likely to take hold.
Treating powdery mildew
- Once powdery mildew really sets in, it is very difficult to eradicate organically. If it is towards the end of the growing season you might want to consider removing the effected plant to protect other plants in the garden which might still be producing fruits or vegetables.
- If you do remove the plant, make sure you dispose of it appropriately. This is one instance where you do not want to compost those leaves. The fungus spores will lay dormant and potentially spread into next seasons plants.
- Pruning- at the first sign of powdery mildew, we remove any affected leaves. We inspect our plants daily for pests and fungal infection.We have found powdery mildew is more prevalent on Bush varieties of cucurbits, like the bush crop zucchini. In contrast, our climbing plants which are almost at the roof of our balcony are not affected at all. This is probably because they have a lot more sun and airflow. We have heavily pruned back the bush crop cucurbits which has extended the growing life of those plants.
- You can treat powdery mildew with an organic spray like Neem oil however Neem oil may be toxic to the pollinators like bees or butterflies so it should only be used very lightly and should be used at the end of the day once the pollinators have finished work. Be very careful not to spray any flowers with Neem oil. If possible, use a mesh to cover your plans for 24 hours after using Neem oil.
Your crop yield should increase with powdery mildew prevented or under control by following the above steps.
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