Hi Tui, some of the leaves on my rose bushes (from about half way down the bush) are turning yellowish and falling off. I have sprayed then regularly. I looked up pictures on the internet and the only thing it looks like is downy mildew but it is the wrong time of the year. Any suggestions? Thanks.
Hi Beryl, Downy Mildew is a fungal disease that is spread by wind and water splash. It is prevalent in warm humid conditions and so depending upon conditions, it could be affecting your roses at any time conditions are right. It usually affects the buds and new foliage as well, not just the lower leaves. Downy Mildew can remain in the soil from fallen leaves for a period of time so it is important that infected plant material is removed from around the plant to help prevent the spread of the disease. Make sure there is good air circulation around your roses, thin out some of the foliage if they are dense as poor air circulation increases the humidity around the the plant, conditions fungal diseases thrive in. Because it is the lower leaves, and without a photo to know exactly what the leaves look like, it is more likely the roses have dried out at some stage and have not had enough water or irregular watering, it could also be weather related with high temperatures some days. Roses like deep watering every couple of days to encourage the roots to penetrate deeply into the soil so that they stay cool and moist over the drier months rather than light watering which encourages a lot of surface roots that can dry out quickly. Mulching around your roses will also help conserve soil moisture and keep the roots cool and moist, Tui Mulch and Feed is perfect for roses, it feeds the soil as well and contains sheep manure, blood and bone and Saturaid to help water penetrate down into the soil. Feed your roses regularly with a specialty fertiliser in spring and again in late summer-early autumn, this will promote flowering for next season. Water fertiliser in well. Using Tui Organic Seaweed Plant Tonic or Tui Seaweed and Fish fertilsier regularly will also help maintain healthy roses throughout the season. The Tui Team.