Beware Of Moss In Lawn

The increasingly heavy overnight autumn dews in the UK create ideal conditions for moss establishment (or re-establishment!). Spores which have lain dormant during the summer months become active and can soon overpower even the healthiest of lawns. So we need to beware. Now is an ideal time to get down close to the turf and examine it carefully for strands of moss.

If moss has previously been a problem, I recommend an application of ferrous sulphate (19% soluble sulphate of iron) at 1 ounce per gallon of water per 10 square yards (35g per 4.5 litres water per 9 square metres). With the right rose, it doesn't take long to apply with a watering can (you might need to experiment with different ones to get the delivery rate right). I would give this treatment whether you can see any moss or not; any present will turn black almost instantly. You might be amazed at how much there is.

REPEAT TREATMENT IF NECESSARY
I dealt with moss treatment in great detail last year (see last autumn's lawn posts). But I didn't make it clear that we need to keep an eye out for moss re-establishing after a month or two. If it does, then repeat the treatment. You can do this as many times as necessary.

If you keep 'nipping it in the bud', you will keep it in check without disfiguring the lawn. i.e. the dead moss will quickly grow over, so there should be no need to rake.

RAKE OUT IF NECESSARY
If moss is really bad, then now is the time to kill it off and rake it out. There is still time for the turf to at least partly recover before winter. This way it will not look as unsightly as it would if left till later, or - even worse - next year.

Too Cold For Tomatoes?

The tomato plant is not doing well. All seemed to go well at first. Then leaves started rolling and growth became slow and stunted. Although there are a few flowers and fruits, things should be much better. They started to go wrong after I saw greenfly feeding on the stems. The growing tip rolled up like a clenched fist within days and never recovered.

SAME AS LAST YEAR
This is exactly what happened last year, the only difference being I have not detected any blight (last year's plants had to be destroyed).

These normal leaves are from a cutting of 'Outdoor Girl', given by a neighbour. These plants (he gave me two) have defied all neglect and seem insistent upon forming normal plants.

STILL NO WISER
The fact that 'Outdoor Girl' is a reliable outdoor variety indicates I have been 'flogging a dead horse'. 'Alicante' and 'Ailsa Craig' (last year's variety) just will not grow in my garden, probably because it is too cold and draughty. Although, of course, the greenfly could have brought a virus? I'm still no wiser.

Gibberellins Rampant Under August Skies

August in the UK is a difficult month for fuchsias. If the hot muggy weather doesn't allow botrytis to destroy plants, the sudden appearance of dark thundery skies followed by prolonged warm dull days produces long (leggy) growth through etiolation.

PROBLEMS INDOORS WITH CONTAINED AIR
Things are not so bad OUTDOORS where darkening skies (loss of sun) do lower temperatures more quickly. No. It's INDOORS where problems really occur. Contained air (either by walls or glass) does not cool down nearly quickly enough to accommodate reduced light; the plants 'assume' they have competition, so therefore need a sudden spurt of growth to outgrow this. Hence leggy plants.

Etiolation is caused by elongation of the stem's vertical cell walls, controlled by the growth hormones 'gibberellins'

Not Virus Infection On Dahlias

It doesn't look as if the dahlia leaf problem was caused by a virus (see 'Mottled Dahlia Leaf?'. New leaves are now looking quite healthy after feeding, and the leaf discolouration does not seem to have spread.

GIVEN FEED WITH TRACE ELEMENTS
Dahlias are often short of trace elements at this stage of growth, and applying these usually significantly brightens flower colour. Seaweed feeds are very good. But I used good old 'Phostrogen' because its analysis shows it not only contains trace elements but is also rich in potassium, which is also beneficial for flower production.

ALSO SPRAYED FOR THRIPS
I also sprayed with thiacloprid to control thrips. This should also control aphids (which spread viruses) and other pests till the end of the season. Pity it doesn't also control snails!

Notches In Leaves

Beetles and weevils damage leaves by biting chunks (notches) out of them. Vine weevils - and sometimes chafer beetles - are a particular nuisance at this time of year.

Vine weevils love to lay eggs in pots of favourite plants. These eggs hatch into white maggot-like grubs with brown heads, which devour fresh white roots and subsequently kill the plants. Although vine weevils have a seasonal life cycle, in practice they can are usually present in some stage of development at all times of year.

CONTROL MEASURES
The adult weevils can get almost anywhere, and can even climb polished glass. So this somewhat limits control measures to surrounding pots with water (weevils can't swim!), greasing sides of pots, trapping adults with upturned seed trays or similar dark vessels (they shelter in them overnight), or chemical control.

Chemical Control
I treat all pots and susceptible plants with thiacloprid. I know it's a carcinogen, but it gives good long-lasting control (several months) and also controls many other pests such as aphids and whitefly. But, most important - it kills vine weevil and chafer grubs.

Mottled Dahlia Leaf?

Wonder what's caused this yellowing on this dahlia leaf? Haven't seen it before.

MAGNESIUM DEFICIENCY?
Yellowing between the leaf veins is often a sign of magnesium deficiency, so could be this in an early stage. Doesn't seem likely, but given a dose of trace elements just in case.

VIRUS?
Mottling is often associated with virus disease. But this is also unlikely, as I haven't seen it before, and haven't brought any new plants in. But could have been there all along and is now showing up because of recent stress (plants have never been watered, apart from rainwater)

THRIPS?
Seems strange that it is only now noticeable after much rain and thundery hot weather. Might be thrips (thunder flies) damage, though haven't seen any. Another mystery. Will have to wait see what develops.

Signs Of Over-Watering Triphylla Fuchsia

The yellowing leaf tips of this triphylla fuchsia are a sure indication something is wrong. Because they have appeared following torrential rain, it is likely to be over-watering. Check the roots.

Sure enough, this reveals poor growth at the base of the pot and patches of brown dying roots - a sure sign of over-watering. The compost is still dark and soggy.

REMEDY
Good job the weather has been cool, or damage could have been much worse. Had browning become so bad that the roots had begun to smell, then replacement of the bottom compost would be necessary. However, because we have tackled the problem early, just drying out on a paper towel, then replacing into pot, should sort things. It will not remove the yellowing, but new leaves should be fine. New roots will soon grow into the damaged areas.

PREVENTION
Adding more perlite (and even grit) to the compost (25%) might have prevented the problem by allowing better drainage and aeration. Protecting the plants by covering the foliage with clear polythene bags, as outlined last year, is also a great help.

Troubleshooting Furry Mould On Fuchsia Stem

This furry mould on a ripe (woody) fuchsia stem is caused by Botrytis, a pathogenic fungus. Botrytis is a problem with fuchsias in warm muggy weather and in cold damp, still air. I spotted this yesterday and sprayed with 'Systhane' (myclobutanil). Doesn't look like it's having much effect.

If left alone, the branches die back one by one, until the fungus has destroyed the whole plant. If caught early enough, it can sometimes be cut out. However, it is often too near to the base of the plant (usually on the main stem) for this type of control.

It often starts from old decaying plant material left lying on the surface of the compost, then travels across the compost to the main stem of the plant. It is also often found at the point where a branch has been cut back and bleeding has occurred, leaving sugary sap on the stem around the wound. This is ideal food for the fungus.

Cuttings in too wet compost can also suffer due to the organic matter in the compost, which feeds the fungus. Best to use sterile perlite and water at this time of year.

PREVENTION
It seems this disease can only be contained by preventative measures applied BEFORE the fungus penetrates the plant tissue. i.e. only CONTACT fungicides and husbandry techniques are effective.

• Myclobutanil (a systemic fungicide) does seem to work on botrytis, but as a PREVENTATIVE only. Spraying it on the foliage and compost surface BEFORE ATTACK will offer resistance, just as a contact fungicide will do. So will a drop of two of bleach (chlorine) per litre of water used in the same way. This prevents the spores from germinating. I tried watering the pots with chlorinated water last year but, at the concentration used, it was only successful on older, established plants.
• Keeping the foliage and compost surface DRY is most effective. Should watering be necessary (and it often won't be), it can be done from the bottom by standing the pots in a saucer of water for about 20 minutes.
  
• Do not cut back stems too soon after watering. Best if this can be done when plant is near wilting point, just before watering (allow wound to heal first!).
  
• All dead leaves and other debris should be removed as soon as possible, before they become infected.
  
• Ventillation is useful when plants are inside, especially in winter. But botrytis also affects plants outside in the summer months.

White Powder On Fuchsia Leaves

Fuchsias have their own way of dealing with overfeeding - they're sick. That's what has happened here. Excess mineral salts have been exuded by guttation and have dried on the leaves, leaving a white powder which can be washed off with water.

Preventing Tuberous Begonia Stems Breaking

Tuberous begonia stems can be extremely brittle and easily break off where they join the tubers, especially when knocked or rocked by high winds. Discreet staking gives support and helps prevent this.

Take care when inserting the cane that you do not damage the tuber. I usually insert them at an angle, so that the base is well clear of the side of the tuber. The stems can then be tied quite loosely (though with a slight tension on the stem), allowing room for stem thickening. As the plants grow, either insert more stakes as necessary, or replace with longer ones.

Feeds too high in nitrogen gives long growth, making the foliage top-heavy. Using high potash feed will both harden the tissues and produce shorter growth. It will also help flower colour and numbers. You don't need much - just one or two feeds will do. Tomato feed is high potash. But I always use 'Phostrogen' with every feed. However, although this produces wonderful plants, they still need staking, but not so much.

MAKE A SHOOT TIP CUTTING FROM THE OLD STEM
Provided you get to the broken stem in time, you can make a shoot tip cutting as shown in earlier posts, either using compost or perlite and water. Cut stem under water (to prevent air bubbles) about 6mm (1/4 inch) beneath a node. Then leave in water for about 4 hours. Some growers actually root in water, though I have never tried this - except for perlite and water, which seems to work well and was outlined recently.

The problem with begonias is that they only grow very slowly. So best to remove all flower buds on new plant, to give the new tuber as much chance as possible to develop before winter. I would again use 'Phostrogen' to produce good growth of both leaf and tuber.

Dead Spots On Lawn

Spots of dead grass, about 2 inches (5cm) diameter, on a summer lawn are usually caused by 'Dollar Spot Disease'. Gradually, these coalesce into larger dead patches which are very disfiguring.

This is a fungal disease in which the leaves of the finer grasses (especially those of creeping red fescue and cumberland turf) die back in hot muggy weather. Normally occurring in August in the UK, last weekend's weather will have caused the problem.

CONDITION NOT TERMINAL
The condition is more cosmetic than terminal. Rake out the dead grass. Once the weather cools down, apply a feed if necessary. Things should then be fine.

Note that small dead spots can also be caused by other things such as petrol drips.

Fluted Leaves On Dahlias

These fluted leaves are on the 'drought resistant' dahlia started earlier in a tray (see 'Dahlias Started In Trays Are Short-Jointed')

Given that the plant has received no water from me whatsoever - even at planting - apart from a couple of inches or so of natural rainfall (dahlias usually need at least an inch per week; perhaps more), it is easy to suppose it is fluting its leaves because it is desperately thirsty.

And if I were to tell you it has still received no water from me and, furthermore, having stood under the blazing sun for another couple of days, it is still standing and not looking too bad, you might think I'm kidding you. I am not. Although heavy rain is imminent, as I write this it has not arrived.

When I first saw the fluted leaves, I thought the plant was short of water. The loose surface soil looked like dust. But the leaves were firm, not limp; and on digging down a couple of inches, I could see some moisture. Even so, I think I would have still watered the plant had I not been determined to see how the dahlias will turn out without giving ANY water apart from natural rainfall. It's been a bit of a bare-knuckle ride - but so far, so good.

We saw last year that begonias flute their leaves as protection against strong mid-summer sun. I haven't noticed fluting on dahlias before. But it looks like they might do the same thing - especially when water could soon be in short supply.

Blight Danger

High temperatures (25 deg C) and humidity forecast this weekend. Best get tomato plant sprayed with 'Dithane' (mancozeb - a contact fungicide). But there's a problem in wet weather - it tends to wash off too quickly before temperatures high enough for blight to be a danger. This is what happened to tomatoes last year.

Slug Eggs

Found this group of presumably over-wintered slug eggs in a container. Slug eggs resemble little dark yellow pills about 3mm diameter. Although laid in groups in a damp spot just beneath the soil/compost surface, they are also laid amongst the roots and tubers of over-wintering plants and are a particular problem with dahlia tubers because the slugs hatch out just as the tender young shoots are emerging from the tuber. Slugs can do massive damage to young plants in a very short space of time - they need watching, especially in damp, warm conditions.

If buying plants from a nursery, do not confuse slow-release fertilizer granules with slug eggs. They are about the same size, but slug eggs are definitely dark yellow.

Sun Scorch (Sunburn) On Begonia Leaf

This is sun scorch (sunburn) on a begonia leaf, common at this time of year (midsummer) when moving plants too quickly from shade into strong sunlight.

Although plants are classified according to their light preferences - e.g. shade-loving; sun-loving etc - this is not absolute. We saw last year that, given time, plants can adjust to almost any environment (see posts on 'light').

PLANTS TAKE IMMEDIATE AVOIDING ACTION
Although begonias do not seem to be able to do this very well, plants can often react quickly by altering leaf turgo pressure (there are different ways of doing this), causing them to either follow or avoid the sunlight. For example, begonias (shade-loving plants) flute their leaves (common with many plants).

LONG-TERM ACTION TAKES TIME
However, they also GROW into their new environment and develop a thick waxy cuticle on the leaf surfaces to protect against damaging ultra violet rays; leaf size is also reduced in bright sunlight, and vice versa.

REMEDY
Leaf structural damage is permanent; they will not recover. However, if the disfigurement can be tolerated in the short term, it is worth leaving the damaged leaves in position because:

• there will usually be some undamaged tissue left which will speed growth of new leaves
• they offer shade to young tender leaves

Avoidance is always the best policy. Covering with horticultural fleece offers immediate shade protection. But best policy is to place plants in right light conditions.

Tomato Blight Protection

Sprayed tomato plant with contact fungicide 'Dithane' (80% w/w mancozeb) to protect against tomato blight (Phytophthora infestans). Still a little early - blight has always attacked my tomotoes in August. As outlined last year (see 'Tomato Blight Update', 26 August), it requires '. . . consecutive 24 hour periods, each with a minimum temperature of 10 deg C (50 deg F) and each with a minimum of at least 11 hours where the relative humidity is 89 per cent or more'. i.e. hot muggy weather.

Contact fungicides are effective over a much wider range of diseases than systemic ones, but must be applied BEFORE disease spores come in contact with plant. They work by preventing spore germination on plant surface and need applying every two or three weeks. Systemics prevent spore germination but also block active metablolism inside plant - so should also be effective AFTER infection has occurred. See also: 'How Fungicides Work'.

Not sure if 'Systhane' (myclobutanil) can be used on tomatoes. It can be a bit fierce. Tested on a single leaf, which seemed to change colour, though not sure if this was due to chemical or to other causes. Bordeaux mixture (copper sulphate) is also effective on potatoes, though again not sure if it can be used on tomatoes. Does anyone know?

Troubleshooting Holes In Rose Leaves

Never ever seen holes in my rose leaves before. Leaf cutter bees bite large chunks out of leaf edges. But this? A complete mystery. The way some of the leaves have holes chewed in their centres upto the veins (these have been left intact), resembles slug, snail, chafer beetle, or sawfly damage (see last year's sawfly problems on euonymus).

Rose slugworms are the yellow-green larvae of a sawfly. But they only usually feed on the lower leaf surface and cause light brown patches to develop. There is no such evidence. It really is a mystery.

Anyway, whatever the cause, healed edges of holes indicate pests have gone - at least for now. Sprayed with thiacloprid 'Provado', anyhow - a systemic (travels around plant within sap) insecticide which gives protection against most rose pests for upto two months. Situation needs watching closely.

Blackfly On Dahlia Bud

It doesn't pay to let aphids - such as the blackfly seen here on a dahlia bud - get out of control; they multiply incredibly quickly, as you can see from the infestation (right) of a black bean aphids on an elderberry branch. Is it any wonder a plant has difficulty coping? And that's aside from the fact that aphids also bring virus and other diseases.

CONTROL
Only certain varieties of dahlia seem to be affected by blackfly. Control as per greenfly and all other aphids, by organic or inorganic methods (see 'Troubleshooting Aphids On Rose Bud').

Pinching out the tip will remove most of the aphids and induce bushiness in this single-stemmed plant. The downside is that it delays flowering. Flowering in dahlias takes about 8 weeks from stopping (pinching out).

Troubleshooting Aphids On Rose Buds

Aphids, especially greenfly, are a real pest on juicy rose buds during a hot spell at this time of year (roses open around the time of the summer solstice). Although there is one adult here (bottom right), we have mostly young greenfly, which are born live (viviparous) and develop through several stages, often shedding cuticles or skins which fall down to leaves below (see 'Old Cuticles Are Sure Sign Of Pest Trouble')


Young blackfly are also present

Aphids need controlling because they spread viral diseases and cause structural damage to flowers and leaves. They also excrete honeydew as they feed (you have probably experienced this when walking beneath the canopy of summer trees) which drops onto the lower leaves and attracts black sooty mould (this is not in fact harmful, just disfiguring).


Also in other colours:

Aphids also come in many other shades and colours


CONTROL
Control with 'Provado' (thiacloprid) for long-lasting systemic action, or organic fatty acid sprays, or soap and water, or water, or remove by hand or . . . there are many treatments.

See also 'Lonesome Greenfly'; 'Blackfly On Dahlia Bud'

Dealing With Moss In A Summer Lawn

Apply Summer Feed First (should control it); Mosskill Later, If Necessary


Treating a lawn for moss is rather like a doctor treating a sick patient. The first thing to do is control the suffering - usually with drugs or other chemicals - then work on changing, if possible, the conditions which caused it. And just like any sickness or ailment, treatment can be applied AT ANY TIME. It's just that some times are more cosmetically amenable than others. Now, the summer, is such a time.

Before I go any further, can I apologise to those of you who tried my autumn moss treatments described last year (click 'moss' link at side), but have found moss re-growing in their turf this year. It's my fault, not yours. I should have made things clearer. In case you are sick of hearing about moss and don't want to read further, here is a quick prognosis:

• keep zapping moss as soon as visible, any time of year
• rake out some of moss if it looks bad
• apply liquid lawn feed (usually all that is necessary)

All pests, diseases and disorders have one thing in common: They are all extremely resilient and enduring, able to resist the most adverse conditions and re-establish at appropriate times. The ways they do this is a fascinating study in itself - one which would teach we humans a thing or two, but this is for another day.

MOSS NEEDS REPEATED TREATMENTS
Consequently, moss is difficult if not impossible to eradicate AT ONE ATTEMPT; it has to be ground down over a period of time with REPEATED TREATMENTS. But hold on. I'm not talking about all the hard work you did to aerate and loosen your turf. I'm talking about another dose of ferrous sulphate in water.

NIP IT IN THE BUD
I'm sorry I didn't make clear that you need to watch the turf closely for signs of regeneration, then nip it in the bud. This is what I did with my lawn. The moss problem reduced significantly, right from the off. But I then wanted to change the conditions to eradicate it completely.

AUTUMN TURF TREATMENT HAS NOT BEEN WASTED
This is where the turf aeration and top-dressing comes in. It hasn't been wasted. And it's not even absolutely necessary to contain rampant moss - another dose of ferrous sulphate will do this.

As the battle continues, moss is contained to a smaller area of lawn, perhaps just the odd patch or two. This happens fairly quickly. So what I did then was apply ferrous sulphate with a hand sprayer; but if it had spread too far, I treated the whole lawn (this is what I did early last November). Having said this, however, always bear in mind that there will always be much more moss in a lawn than that which is visible. This always seems to be the case. So watch that it doesn't become rampant again once your back is turned.

TREATING SUMMER MOSS

MOSS USUALLY STOPS GROWTH IN SUMMER
Because moss usually thrives in wet conditions (some mosses thrive in dry ones), as the lawn surface dries, it dies back because, unlike the grass, it has no root structure to access water deeper in the turf. This is why you should never water a lawn too frequently with small doses. Water heavily at longer intervals (see last year's lawn posts). It gets the water deeper down for the grass roots, but allows the surface to dry.

HIGH NITROGEN FEEDS USUALLY KILL MOSS
After recent rainfall in parts of the UK, lawn recovery can be enhanced by applying a summer feed. Although this can incorporate a mosskiller (ferrous sulphate), it should not be necessary unless the weather (and turf) is very wet for prolonged periods. To give you some indication, I don't think I have ever used a summer lawn feed with mosskiller.

WHICH TYPE OF FEED
The choice is between granular or liquid feeds. (See 'Choosing A Lawn Feed')

Liquids
Liquids are ideal at this time (they can also contain ferrous sulphate mosskiller), because they soak the grass leaves. When wet, the feed is taken into the plant, so starts working almost immediately (granules take about 2 weeks). But there's another benefit. As they dry on the moss, it tends to be killed (due to plasmolysis).

Liquid feeds also have the benefit that they are more controllable, especially if the weather suddenly turns dry. All this was dealt with last year.

WHAT ABOUT THE UNSIGHTLY DEAD MOSS?
Mosskiller instructions and gardening programmes always advise removing the dead moss by raking. But this is hard work and is usually not necessary.
Many believe that this removal prevents the moss re-establishing from spores (moss's equivalent of seeds) left on the ground. This is not true. Only the heavier metal salts (such as mercuric chloride (no longer available)) will kill the spores (it also kills almost all your soil micro-organisms, as well).

Others say removal makes room for air and light to enter the turf. Well. Maybe it does. But lawn grass will almost always grow through it very quickly. And because moss is soft tissue, it soon breaks down in the turf (unless it's a dry summer, or the turf is very acid).

GIVE IT A LIGHT RAKING
I found that a compromise works well. Rake out some. But you don't need to be too thorough. And only do this if it looks unsightly. It's really determined by cosmetics.

JUST A RECAP

So, starting now, follow last year's moss posts through from beginning, just like last year. Otherwise:

• keep zapping moss as soon as visible, any time of year
• rake out some of moss if it looks bad
• apply liquid lawn feed
  

And, don't forget. KEEP NIPPING IT IN THE BUD. YOU WILL BE SURPRISED AT THE RESULTS.