Mildew

InBloom · August 2022

I'm making an effort to try and spruce up a bit. I've noticed in the back garden there's mildew on a lot of things. The verbena is covered, the tiarella and tellima has it and senecio. I've sprayed things before and killed them, must have been sensitive to the spray but it didn't really get rid of the mildew either. Anything else to do? Or maybe should plant something more resistant?

AnniD · August 2022

I suspect the hot weather is to blame. I have been keeping my Michaelmas daisies (Asters) well watered as they are very susceptible, but l noticed one this morning that I'd missed 🙄.
I use Fungus Fighter spray, l find one "dose" is usually enough, as long as they are kept watered afterwards. .
https://www.diy.com/departments/provanto-fungus-fighter-fungicide-1l/3664715006701_BQ.prd?ds_rl=1272379&ds_rl=1272409&ds_rl=1272379&gclid=EAIaIQobChMI_qedscXD-QIVQuDtCh25ZQljEAQYASABEgIocfD_BwE&gclsrc=aw.ds&storeId=1298

Obelixx · August 2022

Here in France they use a purin made from soaking horse tail/mare's tail weed in water for 2 weeks. Strain, dilute and spray. harmless to insects and cures as well as prevents mildew, peach leaf curl, black spot on roses, tomato blight....

1kilo fresh horsetail, bashed and bruised
9 litres of water

Combine the two in a plastic bucket - not metal - and leave for 2 weeks. Stir occasionally. It's ready when the water has gone black. It will smell so you may want a lid.

Strain the resulting liquid, put the goo on the compost heap and dilute the rest 1 part to 9 parts water and spray.

InBloom · August 2022

I'd not heard of that one obelixx and I used to be overrun with horsetail in my old garden. (thankfully) don't have any of it growing here. But some plants I found just die after chemical spray like it scorches them. Maybe though the issue is not well watered enough. The verbena get it every year, but this year particularly bad I'll try to put a picture on. But even after watering this morning when I've dug plants out today to move things around I've seen I've really only watered the top cm or two. I think I'm underestimating just how much water I need to be putting on

Obelixx · August 2022

Mildew is ever present and takes advantage of stressed plants so adequate watering is definitely a key preventive measure. It may well be too late this year if your mildew is well advanced but is worth a try.

However, the horsetail purin also acts as a preventative andworks on peach leaf curl and some rusts too so worth getting hold of some horsetail to be ready for next year.

Fairygirl · August 2022

I think this is a problem many people in parched areas will be having regularly, and will need to rethink to avoid future ongoing problems with things like mildew. If water's in short supply where you are, and you aren't able to give plants what they need in order to thrive, then it's pointless growing them.
If it's a case of not watering well enough , and you don't live in an area that has restrictions with water, then it's much easier to tackle without resorting to sprays of any kind. Proper, deep watering and then mulching will help, but that mulching would be best done earlier in the season, so that the plants can get a head start if you have long dry spells. Frequent additions of organic matter through the autumn and winter will also improve your soil, and that will also help for those summer months when plants may struggle with serious moisture loss. Even that may not be enough, depending on weather and general conditions in your garden.
Re tiarellas - they'll practically grow in water, so a shady cool, damp site is best for them. The others prefer brighter, drier conditions - within reason, but will certainly grow well in less sunny sites, so perhaps it's a case of relocating them, if possible, so that they don't get fried, and dried out.

As ever, it depends where you are, and what your soil is like to start with, as well as your general climate

InBloom · August 2022

Image: https://us.v-cdn.net/6030279/uploads/editor/mx/yph66ii4tkct.jpg

I think maybe a bit past it for this year it's already quite bad but a lesson to keep better watered next year. This end of the garden is damp and shady but far from damp at the moment and I'm realising I've not watered enough.

So if it's like this now do I stand a chance of not having it back next year without using chemical spray? The tiarella haven't had it before and I know the verbena will be cut right back

Obelixx · August 2022

It would help if you changed your settings to include a general geographical location like @Fairygirl and I have done.

Rather than spraying, try saving water from baths, showers, washing up (unless it's greasy), what you run off before the water gets hot and then pouring that round affected plants. Keep that up for the rest of the summer.

When autumn rains have thoroughly soaked the soil and the foliage of your perennials has died back, start with the mulching programme. Spread well-rotted garden compost, well-rotted manure, purchased soil conditioner and spent compost from pots layering it on 2 to 3 inches deep but not right up to any shrub or tree trunks. Over winter, the worms and other soil organisms witll work it into your soil and thus improve both its fertility and its moisture retentiveness.

Repeat every autumn right thru to spring.

Fairygirl · August 2022

I can honestly say I've never had mildew on a tiarella, so it must be very dry where you have them. Airflow is also important though, and especially if you have a lot of heat, as that encourages it with plants that are too close together.
Verbenas aren't generally susceptible as far as I'm aware, so there's a good chance that's the reason for them getting it so badly. Moist, humid conditions over a long period definitely isn't great for them. It might even be worth cutting them back, to relieve the stress. They're quite likely to come away again with some good watering and some cooler temps.
I don't grow the other two, but someone else may be able to advise re cutting those back - or not.

InBloom · August 2022

I should have said as well there are some very mature trees adjoining and I suspect they drain huge amounts of water out of the soil. Probably not just after rain but even after watering too and that might explain why it's so dry. In the winter and spring after rain it can be standing water just a couple of inches below the surface. So I suppose thinking about it, it's a lot to ask to find things that tolerate it all well. Pittosporum has done the best but it's been very hit and miss what's survived and we've lost a lot.

So in the autumn if I were to empty some grow bags on would that improve things? And chicken manure pellets too?

We feed with blood fish and bone but I realise this isn't adding any organic matter

I've not had mildew on tiarella before either this is the first year

Obelixx · August 2022

Mulch in autumn and winter once the soil is thoroughly wet. Feed in spring when plants come into growth.

Mildew

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