Category Archives: Compost Tea

Information about Actively Aerated Compost Tea, and Links to sites. Link to Bugbrewer site.

Potato Blight and Compost Tea

I hadn’t intended writing a post on potato blight and compost tea to end my posting drought, but I had the opportunity to record the effect of using compost tea on blighted potatoes, and decided to run with it. Please note that if you’ve found this blog searching for remedies or preventative measures to combat potato blight,  I’m not claiming to have found a cure.

Potato Blight Conditions

Periods where potato blight is likely to occur are called ‘Smith Periods’. There’s a good explanation of Smith Periods on the Blightwatch site. I’ve been a bit busy and haven’t been checking the weather forecast, nor have I notified Blightwatch about a change of email address, so was horrified to find that two complete beds of potatoes were showing signs of potato blight. The two beds are shown in the picture below, after treatment.

potatoes in beds

Two beds of potatoes

The bed on the right is a double row of Charlotte potatoes. A lovely second early, salad potato, which should be ready to harvest soon. The bed on the left contains a single row of Lady Balfour potatoes, an early maincrop potato which I grew for the first time last year. Please note that these were taken after all of the treatments that I undertook.

Normally I spray my potatoes with compost tea before any likely Smith periods. I think that it helps to delay the onset of potato blight. I avoid spraying in the evenings, as the nights normally have higher humidity levels, and I want to avoid wet leaves at night. As I mentioned earlier, I’ve been busy with my grain crops, and it completely slipped my mind. The first thing that I normally do once I have potato blight is to cut off all affected foliage. In the picture below you can see how badly the right hand row had been blighted by the amount of leaves that I cut off. Yesterday I started a compost tea brew before defoliating so that it would be ready to spray by the following morning. (Recipe details later).

tTreatment for potato blight

Potatoes after trimming

Note that some of the top leaves had lots of small blight spots, but I wanted to leave a few leaves on each plant. After removing all of the infected foliage the potatoes didn’t look too bad, so I took off the clothes that I had been wearing whilst handling the infected foliage, along with the secateurs, and put them to one side to use for that purpose only, to avoid spreading the potato blight to a third bed in another area, and to the tomatoes and peppers in my polytunnel.

Applying Compost Tea

This morning when I checked the plants more leaves were showing large blotches of blight. I had hoped that the extra airflow may have checked the spread of the disease, but that hadn’t been the case. I then applied compost tea as a foliar spray, trying to wet the undersides of the leaves too. The compost tea was applied at a dilution of 1.9 with water, or 10%. 1/2 liter in a 5 liter sprayer. I have a larger backpack sprayer, but it wasn’t needed for this quantity of crop. 20 liters was enough to treat both rows.

Compost Tea Recipe

I used a simple bacterial compost tea recipe

50 liters of rainwater

500 cl of liquid kelp

500cl of molasses

2 liters of urine (approx)

500 cl of vermicompost

500cl of my best cold compost

500cl (approx)of finely sieved rockdust (basalt)

I forgot that I have made some fish hydrolysate and could have added that too.

Further Treatment

After the compost tea had dried I decided to spray with a kelp and seaweed foliar spray. I can’t really tell you why, but it felt right. My brain rationalised it by telling me that it was food for the plant to help it fight the infection, because the ingredients for the compost tea brew would largely have been incorporated into bacterial bodies. I don’t think that’s strictly true, and perhaps I just wanted to ‘do something’ extra to help.

The Results

A few hours after applying the second spray it rained heavily. So when I went back to check on the potatoes later in the afternoon I was expecting things to have deteriorated. It was immediately obvious from a distance that there hadn’t been an increase in blighted leaves, and in fact the bulk of the foliage looked healthier than it had this morning. A closer inspection of the leaves confirmed that. The picture below is of a leaf that had exhibited  patches of dark brown blight. You can see that the blighted tissue appears to be being eaten away from the center outwards. Where intact areas of blight remain the colour is a lighter brown, and areas of leaf tissue where blight infection had just begun has lightened up.

leaf treated for potato blight

the effect of using compost tea on blight


The picture below shows one of the upper leaves that had been covered in little dark spots of potato blight. Again the blight seems to be lighter in colour, and to be being eaten away.

blight on potato leaf

a leaf showing blight spots

The next picture shows another leaf with the spots almost gone.

potato blight on leaf

More blight spots

Further Actions

I’m going to give the potatoes another spray with compost tea tomorrow, after removing any leaves still showing signs of potato blight infection. I may also remove some more of the leaves from the Lady Balfour row, to give a better flow of air through the plants.


It is impossible to say with any certaintity how much of a role the compost tea played in the checking of this potato blight infection. The potatoes may have fought the infection off themselves. The improved airflow and reduced humidity created by a drastic pruning of the leaves may have been responsible, or contributed. The additional spray of kelp and molasses may have been the main component, which is more simple and quicker than starting a compost tea brew. However I’ve seen compost tea prevent blackspot on new rose leaves after spraying, and my potatoes are normally pretty late in getting blight when I am spraying them regularly with compost tea. It certainly seems like there is scope for a more structured potato blight compost tea trial.


All of the best










Bees and Compost Tea

The last ten days have been hectic, with the extra work down to Beekeeping, and Compost Tea. Just recently, the normal jobs that I have to do on the Smallholding, have been rushed so that I can finish my preparations for the swarming season.

The rush started last week. I went to help a friend check his hives, and we found that one was queenless. There were youngish bees in the hive, so it had probably occurred recently. He ordered a new queen, and later came to the Smallholding so that I could show him how to put together new frames, so that we could carry out a shook swarm, as soon as the Oilseed rape (canola) has finished flowering. I was also putting together hive bodies and frames, ready for making increase of my own stock of bees.

On Tuesday, I had a call from a friend to tell me that he had seen his first swarm, so I continued to put hives together. By Thursday night, I had six new hives, waiting for bees. On Friday I noticed scout bees going into a hive that I had put out the night before. There were quite a few, and I got my camera ready, in case they brought a swarm in. Despite a high level of activity, no swarm arrived. That afternoon I got a call to say that the new queen had arrived, so I went along, and we shook the workers into a new, clean hive, with fresh foundation, and let them settle, before introducing the queen in her cage. We will have to wait and see if they accept her. As they have been queenless for some time, that should help, but I’m not sure how the disruption to the hive due to the shook swarming will affect them.

Scouting activity at the home hive continued throughout Friday and Saturday, and on Sunday morning, but then stopped. I didn’t notice the stop, because I was away giving a presentation on Actively Aerated Compost Tea (ACT), to the Lincolnshire Organic Gardener’s Organisation (LOGO). I think that it went well, and have had orders for at least one Compost Tea Brewer, possibly two. More importantly, I hope that an undersdanding of the Soilfoodweb will help them to grow more successfully. It has certainly helped me over the last two years. I’ll publish some pictures, when they’re sent to me, and perhaps do a short Compost Tea article.

Back to the bees. I’m not sure why the activity at the empty hive stopped. It could be that the bees knew that the weather was changing. Perhaps they chose another site, and there is a new colony not to far away. If the bees were from a managed hive, it’s possible that the beekeeper discovered that the hive was about to swarm, and intervened. If not, once this unsettled weather clears up, those bees are going to go somewhere, preferably into my hive. There were bees from at least two colonies checking out the hives. Occasionally a bee from another colony would approach the busiest hive, and would be chased away. Bees looking at another hive all appeared darker than the first batch.

Here’s a picture of the scouts outside the hive entrance.

Swarming preparation

Swarming preparation

There were more at times, and I also saw bees doing what looked like ‘waggle dances’ on the front of the hive, above the entrance. It would be great to get pictures of a swarm going in of their own accord.

As well as putting together new hives, I’ve built a couple of ‘bait hives’, to try and catch escaped swarms. Whilst I like the idea of feral swarms, many of them die out, if untreated for diseases. When I finish this post, I’m going to do some map work, and plot all of the hive locations that I know of in the area, and use it to predict where the most likely areas are to place the hives.

You can read  a good article about bait hives here         Bait hives

I’ve got to go out tomorrow, and see if I can get permission to set them out in the areas that I identify.

Last year a pest controller said that he would be able to provide me with some swarms, but nothing ever came of it. I thought that I would contact him again, but had lost his number. Whilst looking for it in the telephone directory, I came across another company, working out of the next village. I gave them a ring, only to discover that they had been looking for a local beekeeper to contact when they are called about swarms. If I hadn’t have lost the original number, I would never have known about them. Working on the assumption that I’d better be ready, I built a very simple swarm collection box, only to realise that it was probably a bit heavy to hold in one hand, whilst balancing on a ladder, so I’ve had to buy some thinner plywood, and will work on that tomorrow. The plans that I have seen are a bit complicated, probably for good reason, but I would need to see one, to work out how they were put together. I’ll stick to a more simple design, until I’ve worked out what modifications need to be made.

I guess it’s time to plan the location sfor the bait hives. I already have some ideas, but I find that it’s always better to approach these things without bias, in case there are better options than my original ideas.

Take Care


Pollen + Water = Brood

Yesterday the bees were carrying masses of willow pollen into the hive, and every wet spot seemed to have bees collecting water. There’s no need to open the hive, as this means that the queen is laying, and the hive is well. It’s a bit early to be inspecting bees, and it needs to warm up a bit first, but there’s no need to if you watch what’s going on at the hive entrance.

Here is a picture of bees carrying willow pollen into the hive.

Bees bringing in Willow Pollen

Bees bringing in Willow Pollen

This is a picture of bees drinking from a pot,

bees drinking from a pot

bees drinking from a pot

And from a damp patch leaking from more pots.

Bees Drinking

Bees Drinking

What’s strange is that until recently, all of the drinking was coming from trays that I had left out specifically for the bees. Last week I started to water my plants with compost tea,  which I use throughout the growing season, and for some reason, the bees seem to want to drink it. Strange.