Saturday, 11 June 2016

Leaf Issues

What a start to the gardening year. Plants are showing all kinds of signs of environmental stress.

Tomato leaves curling upwards

Leaves are yellowing, browning, curling, spotting, and streaking. What is going on and what is an organic gardener to do?


Powdery mildew on rose bud and leaves
Powdery Mildew 

Powdery Mildew showed up really early on roses this year. All these muggy, grey days allow fungal spores to form and spread with abandon. 

So what can one do about p/m?

First of all, make sure that you have really good air flow around your plants and water in the mornings, avoiding splash back .... then spray the mildew with either water or milk.

If the mildew is new and just starting off, blasting the new growth with a strong spray of water washes off fungal spores before they take hold and really get going. Do this in mornings or early afternoons only, and preferably on a sunny day so that you are not adding to the problem. 

Spray Powdery Mildew liberally with milk mix

My go-to fix for p/m is always milk spray. It is easy and works like a charm.

Mix 8 or 9 parts of water with 1 or 2 parts of low fat milk. This only works on smooth leafed plants though, not fuzzy squashes or cukes, as the milk coats the fungal spores and chokes them out. Spray liberally so that plant is dripping, repeat in 3 days. I sometimes add a bit of Safer's Soap to this just to help it stick. Do not add soap if you have ladybugs.

 Black Spot on roses 
Black Spot 

Also showed up on roses really early this year, well earlier than ever before. These dry yet humid days are really causing havoc in our gardens. 

For Black Spot, I generally do nothing more than remove the spotted leaves, clean up the fallen ones, water at ground level and make sure that the plants have good air flow between them. This is easiest and completely organic ; ) 

However, as it turns out, I have a wedding on this crazy, most fungal of years, so will have to be a bit more pro-active. Will be trying out Safer's Defender. Apparently if one cleans up the spotted leaves and then sprays liberally, Defender will prevent new spores from taking hold. 

The milk spray also works as a fungal inhibitor, so spray it on once a week to keep away both powdery mildew and black spot!

 Rust on garlic leaves
(this garlic belongs to a friend of mine in Nanaimo)
Rust

Have orange bumps or streaks on your leaves? You have rust. Can also sometimes be yellow or brown in colour, but either way, is a fungal issue that is once again, caused by our humid, grey, cool weather.

On your edibles, if you catch it early enough, simply remove the damaged leaves.

With regards to the garlic above, if only a few stalks have rust, I would cut off those leaves. However, if many or most show signs of damage, is best to lift and harvest instead, as rust will halt any further bulb growth. Do not compost the foliage.  

Leaf curl on tomatoes

Leaf Curl

The cupping/curling that you are seeing on tomatoes, peppers, squashes, etc.. in our region, may be due to insects, but I highly doubt it. Is most likely purely physiological, caused by environmental factors. 

This year, in most all cases, what we have going on here is weather stress. This endless wind combined with cool temps and high humidity, has our hot weather loving vegetables curling their foliage for protection from the elements. 

 Make garbage bag cloches for your heat lovers ... 
Picture from C. Wilson on Pinterest

What can we do about it? Cut back on watering, water deeply but less often, and pray for warmer, sunnier days. Make mini cloches or greenhouses out of plastic bags. As soon as the sun comes out to play and the weather evens out, the leaves will revert back to their normal ways. The leaf curl will not affect your flowering or fruiting.

Too much prolonged heat, as in a greenhouses situation, will also cause leaf curl. This was certainly the case last year.

If you think that your plant is too hot and dry in the greenhouse, water more often and soak the foliage, too. I water the foliage while rubbing the leaves to open them up to take in more moisture.

 Make manure/compost tea for an organic fertiliser
For organic feed recipes, see HERE!

Occasionally, leaf curl is caused by ones own bad habits, either inconsistent watering or over-fertilising.
    
To fix the water situation, ensure that your tomato/pepper/squash is getting a really good, deep drink about twice a week. No shallow watering but instead a deep soak every 3rd or 4th day. If you are growing in pots, try to even out your schedule so they stay moist, watering thoroughly every day or two.  

Do not try to remedy foliage curl with fertiliser, especially the inorganic feeds! Over-feeding plants may actually kill them. If you have invested in good garden soil, you should not have to add any additional food during the growing season. If you have inherited poor soil, feed them once a week with manure/compost tea or top dress with manure.

  
Hang in there, the weather is bound to get better and these problems will soon be in the past.
Fingers crossed!

Happy growing!