Treat Rose Blackspot At Bud-Break With Myclobutanil

This over-wintered rose bud is about to break open. Gave a second spray with myclobutanil to kill blackspot spores arriving on new leaves. Blackspot over-winters on both stems and soil.

Dealing with spores is always easier than dealing with a disease once it has become established.

Coriander After 16 Days

Coriander roots are now about 3.5 cm (1.5 inches) long. They have done well to make so much growth in 4 days at such low temperature.

This is a tap root system; it will be forming lateral roots soon. Since coriander comes from a hot dry climate, a taproot system is ideal to access deep water and nutrients.

Things are starting moving on top, now. The hooked hypocotyls have turned green and the cotyledons (seed leaves) are about to emerge from the seeds.


WHAT'S THE POINT?
The point I want to make by showing you all this is that seed development is deceiving. Were it not for the fact that we can see the roots, we would never believe they had developed to the extent they have. This is why novice growers over-water seeds: As the compost dries on the surface, they believe the roots are still too short to access water deeper in the compost. They are not.

Glyphosate Safe On Moss On Flags

Glyphosate is normally used as a safe systemic weedkiller which is inactivated on contact with the soil. It is supposed to be very safe to all animals (including us) and can, apparently, be used around fish ponds without damaging the fish.

What I didn't know, however, is that it also works on moss - Moss on the flags that is, NOT ON THE LAWN.

Of course, it will work on the lawn, but because it is non-selective it would also kill the grass - and we don't want that (not after all the years I've spend keeping it alive!).

I always have a problem with moss growing on some shady flags, because the birds use it for nesting. And by the time they have finished, the season is nearly over. Consequently, moss builds up year by year.

WHAT ABOUT TEMPERATURE
As outlined elsewhere, glyphosate is extremely good on all sorts of weeds. However, it works best in warm weather, usually in late April or early May when the weeds are growing actively. Of course, the moss is growing now; so I have treated a small patch to see how it goes. About 8 hours of dry weather is needed so that it doesn't get washed off before it can be absorbed.

BEGINNERS NOTE:
'Tumbleweed' and 'Roundup' are trade names for glyphosate in the U.K. But you needn't use a brand name; you can use a cheaper generic brand. Look at the label, usually the front one. Glyphosate will be stated as the ACTIVE INGREDIENT, along with its strength. The cheapest way is to buy the concentrate, make it up yourself and apply with a hand sprayer (e.g. old kitchen cleaner spray).

ALWAYS USE RUBBER GLOVES WHEN USING WEEDKILLERS AND PESTICIDES, no matter how safe they are supposed to be - they can be absorbed through the skin!

Plant Root Growth

It is easy to assume that plant growth occurs evenly all over the surface. This is not the case. It is confined to specific areas and occurs through cell division and cell elongation.


CELL DIVISION
Growth begins with cell division by a process called MITOSIS. The principal type of growth, or PRIMARY (vertical) growth, occurs at the tips of the roots (and shoots) in APICAL MERISTEMS. As you can see, this region is a short distance back from the root (and shoot) tip(s).

The root apical meristem is protected by a specialised layer of hardened cells called the ROOT CAP.

CELL ELONGATION
Once divided, the new cells elongate, forcing the root cap through the soil/compost. Physical growth now becomes obvious. This elongation is not done in the meristem, but in another area further back.

ROOT HAIRS
Further back still, elongation has stopped and some of the root epidermal (skin) cells develop into single-celled structures called ROOT HAIRS. These are used to take in water and nutrients by intimate contact with the soil. Since they are extremely numerous, they have two effects:

• greatly increase the root surface area


• allow more intimate contact with soil - tending to bind fine, structureless soils

Root hairs are very short-lived and only occur close to the root tip. They are typically less than 1 cm (0.4 inches) in length.
STELE
The centre of the root forms the STELE, the specialised plumbing region. This consists of the XYLEM to carry water and nutrients upwards from the roots to the leaves, and the PHLOEM to carry manufactured food (sugars) from the leaves to the storage area (root) of the plant. Other processes, for example the distribution of growth substances, are also accommodated.

Types of Root System

Over thousands of years, plants have developed root systems to cater for their needs. All plants first grow a PRIMARY root which then develops into one of two types:

• taproot system


• fibrous root system

TAPROOT SYSTEM
Most plants develop a TAPROOT system. It is characterised by a tapering central structure from which lateral roots branch off. Sometimes, this type of root consists principally of a long, thick main taproot to store food reserves (e.g. dandelion); and sometimes this is thickened even more and has less lateral roots (e.g.carrot, beets).

Taproots are useful to access deep water and food reserves, and also to anchor tall plants, such as conifers.

FIBROUS ROOT SYSTEM

Fibrous roots systems are characterised by shallower roots of even thickness and profuse branching (e.g. grass roots). This gives an enormous surface area with which to extract water and nutrients. These roots are also good at preventing wind and water erosion, since they come into such intimate contact with the soil particles.

ADVENTITIOUS ROOTS
In monocots (such as grasses) the primary root dies and ADVENTITIOUS roots grow out of the stem ('adventitious growth' means 'growing out of place'). Shoot tip and leaf cuttings also develop this type of root.

Onions and other bulbs have fibrous roots which are also adventitious, since, as we have seen, a bulb is a compressed shoot. It doesn't half get complicated? But fortunately, you don't really need to know all this to grow plants well.

Note: Quite often it is not easy to determine whether a root is a highly branched taproot, or a fibrous root.

Coriander Seeds After 12 Days

I know I showed you this last year. But its so important we should revisit.

In 4 days, and although these coriander seeds in the plastic cup (left) have been placed in a much cooler spot (average temp. about 5 deg C), the roots (radicles) have doubled in size (compared with right, taken 4 days ago) and are now about 2.5 cm (1 inch) long.

Novice growers are often amazed to see so much root development with hardly anything happening above ground. And because we can also see water droplets on the side of the cup, we know the seeds do not need watering, no matter how dry the surface gets. This is wonderful, since we can now at last avoid the 'cardinal sin' of OVER-WATERING, and quickly develop a good watering technique.

BUT THERE'S MORE . . .
I don't know about you, but I was surprised to see coriander growing in such cool conditions. Although, having said this, it is mostly the root which has grown. This is good. Because a low temperature produces stronger, healthier plants.

Note: Coriander seeds are unusual in that they seem to produce two plants per seed (there would normally be only one root (radicle) per seed). No one ever seems to mention this. A coriander seed produces two radicles, each of which will develop into a separate tap root.

Geranium Buds Now Need Watering

These new buds opening on the rested geranium (pelargonium), together with the stronger daylight, mean that watering can be stepped up to support the expected growth. I have just given the first medium watering since last autumn.

Actually, if the weather hadn't been so cold and unpredictable, it would have been best to give more water a little earlier, at the first sign of buds, or even just before. This seems to induce production of larger flowers. As it is, we are now watering for the next flush of flowers.

No Moss In Lawn: Feeding Delayed

Following last autumn's treatment, then a single treatment with ferrous sulphate mosskiller in November, the lawn now seems to be for the first time completely free from moss.

AUTUMN TREATMENT
Of all the things I did last autumn, I think lowering the acidity by adding ground limestone had the most effect. I say this because this was the first time I had done it; I had been thinking of doing it for years, but always shied away on the grounds that it might make the turf susceptible to fusarium disease, and also might create a worm cast problem. So I did it in the end out of sheer desperation.

Thankfully, the news is good on both fronts:

• There seems to be less disease than usual
• There is only one worm cast since the treatment (I did get occasional ones before this)
  

DELAYED SPRING FEEDING
I usually feed with a spring feed with ferrous sulphate mosskiller at this time of year, but I came unstuck last year when the weather turned nasty. So I have decided to delay feeding a week or two longer.

Lettuce Seed Germinating In Soil Cups

5 days after sowing in a cupful of damp garden soil kept at approximately 8 deg C (46 deg F), this lettuce seed shows quite clearly that the root (radicle) is first to emerge from the seed case (testa), complete with delicate root hairs to absorb water from the soil. The white hypocotyl (the part between the root hairs and the seed) has extended. Had the seed been buried, this hypocotyl would also have hooked over to drag the seed case containing the cotyledons (or 'seed leaves') out of the soil as it extended upwards.

GEOTROPISM
Note that even young roots will always grow downwards. They are said to exhibit 'positive geotropism'. Shoots exhibit 'negative geotropism' and grow upwards towards the light.

After 9 days, you can just see the cotyledons (seed leaves) emerging from this seed. Note that they have turned green in the light; the hypocotyl has also turned green. The green pigment cholorophyll is used to produce food (sugar) by 'photosynthesis'. Once this is done, the young plant is independent of the food supply in the seed. This point must be reached as soon as possible.

LIGHT AND TEMPERATURE
Lettuce seeds are sensitive to both light and temperature for germination. We have already seen how lettuce seeds react to light when germinating.

What is also not generally known, however, is that lettuce seed germination virtually 'drops off a cliff' at 25 deg C, with very slow germination even at 26 deg C. But there is also good news: Germination starts at 2 deg C (36 deg F). Peter Thompson shows this very clearly in his excellent book 'Creative Propagation'

Bibliography: Thompson, Peter(2005) 'Creative Propagation 2nd ed' (Pub:USA and UK by 'Timber Press')