Noticed any brown rot this summer?

Nectarine with brown rot infection
Nectarine showing signs of Brown rot

One of the diseases it’s important to monitor at this time of the year is Brown rot. In our part of the world (in southern Australia), our typically hot, dry conditions have not favoured the disease much this year, but we’ve still noticed an occasional piece of fruit with it, as you can see.

If you’ve had a rainy fruit season, you’re at a much higher risk of a Brown rot outbreak. It particularly loves warm, wet weather.

It’s important to pick any fruit that show symptoms, and dispose of it well away from the tree – put in the compost, feed to animals, or cook (after you cut off the bad bits, of course!).

Peaches with brown rot ready to be cut up and cooked

The infection can quickly spread (especially in rainy weather), so monitoring your trees once a week, and removing infected fruit, gives the remaining fruit the best chance of staying healthy. 

Brown rot spreading from one piece of fruit to another in a bunch of president plums

Even in organic gardens and farms, it’s possible to take preventive action to minimise the risk of diseases like Brown rot.

Hygiene (e.g. removing fruit as described above) is one of the most important, but you should also aim to keep a ‘cover’ spray of one of the safe organic fungicides on your trees at all times.

If you only have a few trees to manage, you can quickly and simply do this job with a simple sprayer, as Hugh is demonstrating here. With more trees to manage, you may want a more mechanised set-up.

There are so many spray systems to suit every size of garden or farm, but it can be really hard to figure out which spray system will suit you best, and what’s the best balance between budget and value.

It’s not worth spending hundreds (or thousands) of dollars on a system that’s too big and sophisticated for your needs. On the other hand, you may be able to save yourself many, many hours (and therefore $$) by investing in a system that will do the job you need quickly and efficiently.

It depends on a few things — how many trees you have, your topography (i.e. how steep your block is), what equipment you have available, and your goals for your fruit trees. If you’re hoping to sell some of your fruit, for example, you really need to make sure you can spray quickly, and easily, as often as you need to. We’ve demystified the whole topic in our short online course Choose the Right Spray Gear.

Mending broken branches in fruit trees

Granny smith apple tree with broken branches

We occasionally make mistakes on our fruit trees (just so we can illustrate the theory of course!), like the apples above, or this broken branch of peaches…

Peach tree with broken branch

Branches also break for other reasons like equipment, animals, storms, disease…you name it, in fact!

Once the damage is done, the next question is “can it be repaired?”

If the break has gone all or most of the way through the wood (like the peach branch above), or has been caused by disease and the branch no longer has any healthy wood inside, then the best thing to do is make a neat pruning cut to remove the broken branch (because remember the first rule of pruning is “remove all dead and diseased wood”).

A broken limb on a fruit tree caused by a kangaroo

However if there’s still enough healthy and green wood on both sides of the split that can be brought back together, it’s worth trying a repair.

Remove the fruit (if there is any), bring the two pieces back together and make sure you can get a really good union between the two sides. Then use whatever is at hand to hold the pieces very firmly together.

Split branch on fruit tree bound with grafting tape

In this case the split was on a fairly small branch, and I had some budding tape in my pocket, so that’s what I used!

For a bigger split, for example in the trunk of a tree, you’ll need a more heavy duty solution like these cable ties.

Broken tree trunk repaired with cable ties

You may also need to support the break with some rope or hayband (baling twine) while it repairs itself.

A broken limb supported with baling twine while it heals

Leave it in place for at least a few months, and check back next spring to see whether the repair worked. If not, remove the branch, but if it did, make sure you thin that limb extra hard next year, and supply extra support as well next season to make sure it doesn’t break again.

Taking enough fruit off the branches to prevent these breaks can be very difficult, as it feels awfully destructive to throw all that fruit on the ground.

But as you can see, it’s important to protect the structure of the tree, not just this season’s fruit. If you’re still not persuaded (or not sure how to do it), invest in our short course Fruit Tree Thinning— your fruit trees will thank you!

Diagnosing leaf curl in summer

The dreaded Leaf curl disease on a peach tree

We want to talk about Leaf curl. It’s a common fungal disease of peach and nectarine trees (if you have leaves curling in other types of trees it’s caused by something else).

It may seem strange to be talking about it so late in summer, as it’s a disease that shows up in spring, but bear with us!

If you noticed the disease in your trees last spring, the trees should have completely recovered by now, and grown lots of healthy new leaves (that should look something like the photo below).

Hugh with a healthy young peach tree

However if you’re not sure whether your trees had the disease, it may still be possible to find out, as you may still have remnant diseased leaves in your trees.

They’ll look something like this:

Remnant dead leaves from Leaf curl infection in peach tree

In fact, this can be one of the dignostic tools you can use to help identify whether you had this disease in your trees, in the ongoing detective work we need to be doing to become awesome fruit growers!

These dead and shrivelled leaves are a powerhouse of fungal spores sitting in the tree, just waiting until conditions are perfect next spring to release the spores, and start the disease cycle all over again.

A fresh Leaf curl infection on a peach tree in spring

It’s been often and hotly debated whether it’s worth removing infected leaves from the tree as they emerge in spring, and the answer seems to be no, it doesn’t help reduce the spread of infection once it’s started.

However, the jury is still out on whether removing the remnant leaves in summer will help prevent re-infection the following spring. As always, we err on the side of caution when it comes to practical, hands-on jobs you can do to help your trees stay healthy.

So…get rid of them! Many of these leaves will probably have fallen off of their own accord and rotted away under the tree, but if there are any still in your trees, remove and dispose of them.  

Hot compost is the perfect disposal method, as the high temps reached will kill off the fungal spores, but the organic matter in the leaves won’t go to waste.

Remember, prevention is much better than cure, and hygiene is one of the best defenses we have against all pests and diseases.

Another strong defence is using allowable organic sprays in spring, but it only works if you get the timing right. We’ve included a complete spray program to help you decide what and when to spray in the short course Better Fruit with Wise Organic Spraying.