Thursday, 28 May 2009

A pollination mystery?

Some years ago I grafted a multiple variety pear tree for my parents, the idea being that three varieties on a single tree would cross pollinate efficiently and give a succession of fruit. The varieties were Bristol Cross (as South Wales is very wet compared to Oxford, so a particularly scab-resistant variety seemed a good idea); Dr Jules Guyot and Concorde. The first two are in the same pollination group, and Concorde is slightly later; both Concorde and Dr Jules are reputed to be partially self-fertile, whilst Bristol is self sterile.

This tree has been in about 8 years, but has never produced any fruit. This year it has set a small number of Dr Jules only. For once I was at home to observe flowering, and all varieties did flower, though some of the Concorde blossom did appear to be later than the other varieties. Even so, the Dr Jules should have provided pollen for the Bristol Cross (it obviously flowered this year, as it has set fruit).  Frost shouldn't be a problem as the climate is much milder than here. 

I think the problem with this tree must be some sort of incompatibility between these varieties. I did quite a lot of research before grafting the tree, so I'm quite annoyed the combination has worked out so badly.

The only solution will be to add an appropriate pollinator, either as graftwood or by squeezing in another small tree. It seems a shame as the tree is growing well and healthily and the three varieties seem very well matched in vigour, which can often be a problem on 'family trees'.

Beurré gris d'Hiver nouveau: set

A disappointing sole fruitlet on my Beurré gris d'Hiver nouveau stepover this year despite the copious blossom and wide range of pollinators. Perhaps not surprising as it was only planted last year as a maiden. Still very pleasing to see home-grafted trees coming into production, albeit modest.

Beurré gris d'Hiver (sometimes 'nouveau') appears to be distinct from Beurré gris (syn. Brown Beurre). This description is from 'The fruit manual' by Hogg (1860):

"Beurre Gris d'Hiver (Beurre Gris d' Hiver Nouveau; Beurre de Lucon).—Fruit large, roundish. Skin entirely covered with thin brown russet, and tinged with brownish-red next the sun. Eye small, set in a very shallow basin. Stalk short and thick, inserted in a small cavity. Flesh white, melting and juicy, sugary and slightly perfumed.

A good late pear when grown in a warm situation, but otherwise coarse-grained and gritty. Ripe from January till March. It is best from a wall."

The Fruit Manual, Robert Hogg, 1860

I hope the singleton survives so I can find out whether Hogg was right or not.

Fondante d'Automne: set

Another promising set of Fondante d'Automne. The fruitlets are particularly highly coloured this year. So far I've found this variety to be prolific and reliable, although the growth is a little on the weak side. Perhaps it benefits from the warm location, with lots of heat reflected off the south-west wall of the house in the summer and early autumn.

Morettini: set

After losing such a large percentage of the crop to pear midge, I'm relieved to see there is still a fairly decent crop remaining. I found only one blackened fruitlet that the midge larvae had vacated, though this will still probably result in enough adults to ensure a bad attack again next year. I will hoe underneath regularly as an extra measure.

Pear : Sierra - failed graft?

I'm beginning to despair of both grafts of 'Sierra'. Whilst those of Passe Crassane, made in the same session, have romped away and are now virtually indistinguishable from the parent growth, neither graft of Sierra is showing any signs of having taken. The scions haven't started to shrivel yet, and the buds are still green so there is still a small chance.

St Edmund's pippin: set

A good set on St Edmund's, several spurs with nice healthy fruitlets. Having read up on this variety and found it described as a 'tip and spur bearer' in a number of sources, I decided to grow it as a cordon. My experience has been that it's entirely a tip bearer so far. However, as it's fairly biennial, I think I might get away with pruning hard every other year, then leaving the fruit to develop on the tips of the previous year's growth.

Irish Peach - set

I'm really pleased to see a good set on Irish Peach. This was one of the trees I rescued from the vandalised orchard on the smallholding; I was forced uproot it very late in the season, and it was touch and go whether it survived last year. It has set a good crop for a small tree this year.

Superb display

Not a great photo but I am pleased with the non-fruit plantings in my 'pear garden'. Shrub roses Scarlet Fire and Rosa Moyesii 'Geranium', growing into half-standards of Pear Morettini and quince Sobu, clashing with Papaver orientalis Turkenlouis'. Contrast added by purple hues of Lysimachia Ciliata 'Firecracker', various purple-leaved sedums, Iris 'Black Swan' and Allium christophii.

Both roses produce decorative hips in later on, though I'm slightly disappointed with those of Scarlet Fire.

Red Comice - espalier

Having removed the top tier of this espalier, I'm really pleased to see strong extension growth in just about the right place to establish another tier to the espalier. I love the colour of this variety's foliage, almost a coral red maturing to bronze. It's particularly vibrant with the other colours in the front garden (Red shrub roses, valerian and Lysimachia ciliata 'Firecracker'. Cropping hasn't been terribly good so far, but I think it will improve with time.

Pear: Rogue Red - set

Another experimental graft, just a single spur of a little-known variety, Rogue Red, from wood supplied by Brogdale. This is the first year it's set a crop (I think the squirrels knobbled ALL of last year's set) so I'm crossing my fingers for this year. I think only the three larger fruitlets will survive and not drop. 

So far, so good; the crop looks healthy, unaffected by scab or any of the pests that troubled other varieties on this row of cordons.

Sucrée de Montluçon - set

Another lovely sight, a very good set of Sucrée de Montluçon, grown as a stepover in my front garden. So far proving a very attractive, productive and healthy cultivar, free-spurring with compact growth which is ideal for training.

Devoe - set

Something to gladden the spirits, a good set of healthy fruits on Devoe. I think this is a lovely variety, the fruit is very attractively striped red/yellow when ripe and is a beautiful shape to my eye also. The growth habit is also good, free-spurring and compact and free from scab.

War on squirrels

This is another excellent example of squirrel damage on a pear crop, this time on my only crop of Dr Jules in 5 years. Although holes and shallow depressions can also be caused by moth damage, there are clear incisor teeth marks. The trap goes out first thing tomorrow before they ruin the remaining fruitlets.

More Fruit-mining Tortrix damage?

Now that the fruitlets are growing on, more caterpillar damage is becoming evident. I think a fair number will actually survive to produce usable, if blemished fruit. 

Powdery Mildew - apples

I grafted a single spur of Roter Ananas onto a half-standard of a different variety about 4 years ago to evaluate this variety, but every year it succumbs to powdery mildew just as the fruit sets, just about the only apple cultivar I grow which suffers. The parent variety is completely unaffected.

Pear Scab

As usual I'm kicking myself for not spraying for scab. Only a couple of pear varieties are usually affected, Conference and Santa Claus. The damage on the former (bottom) is usually just cosmetic, though last year all the Santa Claus were inedibly dry and corky.

Friday, 15 May 2009


The moth larvae attack is turning out to be quite bad, lots of fruitlets bored or nibbled on the outside. Mostly on the Conference/Concorde cordons, with minor damage on the adjacent Comice/Beth (an one or two nibbles elsewhere). 

However, there remains the dilemma of what to use. I've never had cause to spray for insect attack before, only the occasional dose of Bordeaux on scab-susceptible varieties.

Derris is the only insecticide recommended by the Soil Association. The active ingredient is Rotenone. However, all rotenone-based insecticides were banned for public use last year, presumably due to the suspicion they might cause nervous system damage.

The only other choice are Bifenthrin-based inseciticides (Bug Clear), a pyrethroid compound which is also a neurotoxin. Just because such insecticides derive from plant-based substances does not make them any safer, ethical or 'natural'. Bifrenthrin isn't terribly water-soluble. Hopefully that means it won't leach straight into the water table. However, it means it's more likely it will persist in the environment.

In the end I did spray only the Conference/Concorde cordons with Bifenthrin/Bug Clear this morning. We have no Blue tits nesting this year, may be they had kept the infestations at bay in previous years, and my fear is a explosion in the population if the pest goes unchecked in this season. Hopefully this will redress the balance, and the birds will be back next year. The fact we've also had a really bad attack of Gooseberry sawfly for the first time in the last decade suggests there is some change in the pest/predator balance this year.

I'm not going to rant about 'elf and safety gorn mad. We don't know what the effects of these substances are in the environment because ecosystems are enormously complex and difficult to study. Years ago, arsenate of lead and nicotine were popular and highly effective insecticides. On the other hand, pests can destroy whole crops and commercial growers will all spray regularly as a preventative measure so the fruit-eater doesn't escape the issues either way.

Sunday, 10 May 2009

Non-Orchard garden

Reading through the list of bugs and losses I thought I'd cheer myself up with a couple of photos of the main garden. These were taken in May 2007, before the July floods that killed about a third of my herbaceous plants, though mercifully none of the fruit trees. I did have thoughts about NGS opening, but there's still a long way to go before the replanting is mature.

Fruitlet Mining Tortrix?

Another new nasty today, I think it's probably a Fruitlet mining moth (Pammene rhediella ) though I have my doubts as the colour and 
season seem slightly wrong. 
Which ever species it it, this one is 
rather more damaging, as it bores right into the fruit. 
I've only found it on Conference so far, perhaps because the long 
fruitlets are set close together, giving it more shelter. It usually joins two fruitlets together with silk, which is the best clue to spotting it.

More on the various Tortrix moths

Saturday, 9 May 2009

Fruit Tree Tortrix Moth

Curled leaves, which usually unravel to reveal a medium-sized green caterpillar (Archips podana, the Fruit Tree Tortrix) usually sitting amid a web of silk and frass of droppings. 

Not a lot to be done, especially as the leaves bound with silk are an excellent way of escaping any spray treatments. I usually pull curled leaves off when I find them.

More in general about fruit tree caterpillars

Unidentified guests

I have been wondering what had been making small holes on the leaves of a couple of pear cordons; the culprit is a looper-type caterpillar about 4 mm. It's not a Winter Moth Caterpillar. The holes don't really affect the plant that much so I will leave them in peace.

Another small brown looper caterpillar (about 8mm, NOT a mottled umber moth) has been slicing the edges off small pear leaves; again, it's not doing any real harm so I'll leave this one for the birds too.

More Pear Midge

More bad news on pear midge infestation. I got a stepladder to investigate the top of my half-standard Morettini and found an even greater number of infected fruitlets at the top of the tree. This tree did not set any fruit last year as it flowered in January, so the midges that infected it must have travelled a fair distance.

I also found infected fruitlets on Winter Nelis, Sucrée de Montluçon and Fondante d'Automne which showed no outward symptoms other than looking slightly dehydrated (example far left). I would not have detected any on Winter Nelis if I hadn't carried out random checks. Round/conical varieties don't seem to change shape or size as greatly as the pyriform/calabasse types do in reaction to the larvae.

Passe Crassane: graft

The extension graft of wood from Passe Crassane made to one of the front garden step-overs is now virtually indistinguishable from the rest of the cordon, with strong growth. I will leave the pegs and tapes on for a while longer, until the new growth hardens a little more.

The two scions of Sierra haven't yet shown any signs of breaking, though happily there is no shrivelling visible yet, which gives me some hope they will eventually take. 


April showers (which usually come in May these days) afford the perfect opportunity for snail to emerge and creep up trees where they can graze at their leisure, taking large chunks out of pear fruitlets. They can be quite difficult to spot, crouching under leaves and under branch joints. Start to look for them following the first downpours following flowering.

Friday, 8 May 2009

Pear Midge: Further information and links

RHS Leaflet Pear Fruitlet Gall Midge

Some good information here. I haven't found it to be the case that mid-season varieties are unduly affected, two of the earliest to flower (Morettini and Devoe) have been the worst affected this year. There is definitely a marked difference in susceptibility in some varieties, as adjacent cultivars flowering at exactly the same time have remained unaffected. Now that an infestation pattern seems to be emerging, I will probably consider spraying the most susceptible varieties next year, as pear midge can eventually result in significant losses. Whether spot treatment of affected varieties only will be effective in reducing adult midge numbers remains to be seen.

The usual un-informed musings from the team. It much easier to control the maggots BEFORE they emerge and crawl off into the environment (see below for further reasons why leaving the maggots in situ to cause maximum damage isn't a good idea). I see no evidence that it is a self-limiting problem; in my experience it tends to increase in severity over time particularly where control is lax or difficult.

Excellent information here (particularly re. the mobility of the larvae in the environment). Very interesting to read that the presence of infected fruitlets can have a negative effect on the development of the unaffected percentage of the crop; I've certainly found this to be the case on my in-laws' Conference which invariably loses the whole crop by June. Most plant Galls are triggered by chemicals secreted by the infecting larvae, which deliberately encourages abnormal excess growth. Yet another reason to exercise vigilance and remove all affected fruitlets as early as possible. 

Re. 'biological controls' I have to say that poultry don't appear to have much effect on mopping up midge grubs, or any other pests for that matter; the last place my hens ever want to scratch around is in the vegetable garden or under fruit trees.

Gooseberry Sawfly

Not an orchard-fruit pest as such, but returned this week to find one of my gooseberry cordons almost entirely stripped of its leaves by sawfly larvae (variety: Invicta). I haven't had this problem for over ten years, and I wonder if it might be related to the fact this is the first year for many we have no blue tits nesting in our boxes. Another cause might be that this rather middle-aged plant is a little stressed by intensive cordon-culture, as there is also a bad aphid infestation of new growth.

I think we'll just have to live with it as I don't particularly want to spray. I'm not a huge fan of culinary gooseberries and I've never had the problem on Whinham's Industry, the only other variety I grow.

Pears: Squirrel damage

It might come as a surprise to most people that the very worst pest of orchards is the grey squirrel, in urban or semi-urban areas at least. Most people are completely unaware that much of a crop can be lost this early to squirrels. If they do spot the damage, it's usually misattributed to birds.

Squirrel damage is very easy to identify. If you look carefully you can see two identical upper incisor marks, with a 'spooned out' mark above made by the lower incisors. Other fruitlets in this cluster just show tooth marks which match. Squirrels rarely eat the whole fruit at this stage, but can fatally damage a large number by 'mouthing' them out of curiousity.

Two year ago I was not at home to monitor the problem at this stage, and lost the entire crop from my 50-odd cultivars. One pear, two apples and no plums, the entire result from a sizeable, mature orchard. The problem is largely due to a particular neighbour who has numerous bird feeders that are not squirrel proof, and the population had grown from a single pair to numerous competing ones over the exact time period that has been excess supply food in the environment. I trapped and disposed of 10 squirrels last year, and this had a very positive effect on the crop which was very large despite a particularly poor growing season.

This is not something I like doing, but it is impossible to get worthwhile results from fruit growing where there are significant numbers of squirrels. They are also a serious pest of nesting birds particularly where there are population explosions. It may be a coincidence but since the recent spike in squirrel numbers, the reed warbler population in the lake complex that neighbours our garden has crashed; the squirrels have easy access to the reed beds from many poorly-managed fallen willows. Peanut feeders also encourage Greater Spotted Woodpeckers, of which we have 2 nesting pairs currently; these are also voracious predators of smaller nesting birds and have pecked their way into our blue-tit boxes and eaten all the chicks on several occasions. 

Another instance of Pear midge

Another example, this time on Morettini which shows how variable the presentation of the problem can be. The fruitlets don't swell up but develop a bumpy, irregular appearance. Normal ones have an even red flush, but affected fruitlets show an uneven colour. On some, the stem-end has started to become a little flaccid too. The infestation on this tree is particularly bad, probably about 25% of the crop. The entry hole is visible on this one.

Regarding prevention, removing ALL infected fruitlets asap is the only effective control in my opinion. Books will suggest cultivation of soil under trees as a way to control the problem. All my pear trees are grown in soil that is cultivated and whilst this might have been one reason the problem has been slow to develop here, it hasn't prevented it from increasing in incidence. I've dismissed spraying as an option as it is unpractical to do all the trees, at least for the time being. 

It should be possible to find and identify a large number of affected fruits on cordon-grown pears. The problem is that because there is so much variability in the way the grubs affect the appearance of the fruit they infect, it can be easy to miss on a variety that hasn't suffered before. It's also a bit demoralising to cut open slightly bumpy fruits only to find that they are unaffected and lose yet more fruit. So far there has been a fairly predictable pattern to the infection: Comic, Conference and Devoe had single fruits affected sporadically over the cordons (usually the earliest central fruits in the cluster); Morettini has whole spurs affected, and this was also the case with Fondante d'Automne a couple of seasons back. This year I have only found one fruitlet affected on the latter, no doubt I have missed some. 

In contrast, my in-laws 15 year old Conference has had the entire crop affected for several years now, every single fruit turning black and dropping by the end of May, even the few not affected by midge larvae.

Pear Midge

The first casualties of the season. This is a very good example of a fruitlet infected with pear midge. The variety is conference, and there is a very clear difference between the rounded shape of the affected fruit and the pyriform shape of the others. Also, there is a clear entry wound in the form of a small, darkened dot, though this isn't always easy to find when culling potentially affected fruitlets.

Cutting open reveals a wriggling mass of the grubs.

Midge hasn't been too much of a problem here to date. Only certain varieties seem to be affected, though whether this is due to a particular susceptibility or just that these happen to be at the right stage for the midge's cycle is unclear.