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Hi All,

The ‘glorious 16th’ as it used to be known, a time of year as a kid that filled me no-fishingwith excitement because it’s the first day of the fishing season on rivers (closed season is from 15th March to 15th June), but in the old days, all waters, had a close season when no fishing was permitted. So today would have meant an end to 3 months of fishing abstinence and unparalleled excitement on my part, often manifesting itself (I’m ashamed to say) as an early departure from school to be on the river bank !  (Before you say it, that’s not why the blog is so late today !)

Well not a bad week, last week, warm, dare I say hot temperatures and some pretty hefty thunderstorms to boot. This week appears better than I forecast it last week, because the high pressure has strengthened rather than weakened, so that means settled and dry weather on the whole, but it’ll feel cool along East coasts due to the wind direction…

Quite a lot of feedback from my query regarding TE usage and efficacy, with the majority of replies (by comments, emails, etc) supporting the contention that higher rates of TE are required nowadays than previously to achieve the same degree of plant growth regulation.

Ok onto the weather, so how are we looking for the rest of the week / coming weekend ?

General Weather Situation

The biggest factor this week is the wind, or more specifically the direction of the wind which will dictate daytime temperatures. Since Saturday morning it’s been coming from a north-easterly direction and that means it’s a cool wind because it brings cloud cover in from The North Sea for many and this pegs temperatures back quite effectively. So the west and south will see more of the sunshine, certainly earlier in the week (and that includes Ireland). Where the wind is light and cloud cover breaks, temperatures should push up into the low twenties, where the cloud cover remains, it’ll be nearer high teens and on eastern coasts, you may pick up some rain / drizzle in the Haar and it’ll feel cool on the whole.

For many this week Monday will be the coolest day and from then on temperatures will pick up as more breaks appear in the cloud, so a really simple forecast for this week. Most places will be dry, warm and sunny if the cloud cover breaks and a little on the cool side especially earlier on in the week if it doesn’t. The wind will be mainly from the north-east / north for most of us but later in the week it should moderate and that’ll allow temperatures to pick up.

Rain I hear you say ?, nope save for some drizzle off The North Sea and a weak rain front coming into the north-west of Scotland on Friday, it’ll be a dry weak for all of us. Will it last to the weekend ?, will it heck, as that northerly airstream is looking to pick up cooler, wetter air for Saturday, so a drop in temperatures and rain is on the cards, particularly for Scotland and the north counties of Ireland and England on Saturday / Saturday night for the latter. Further south and west, it’ll remain warm for Saturday, but into Sunday that cooler air will sink south accompanied by an easterly wind and this is set to affect most places, dropping temperatures back by 4-5ºC….so a mixed weekend is on the cards depending on where you’re situated…

Weather Outlook

We look to start next week with a cooler, slightly unsettled feel to the weather with a chance of moisture particularly in Scotland and the north-east of England. Next week is finely-balanced between the low and the high and it looks as though initially a new high may push temperatures back up again after the weekend but I think there will be an increasing chance of some rain appearing from Tuesday next week….

Looking at the projections there’s a crafty little Bay of Biscay low set to develop in the early part of next week and if this is so, it’ll bring in wet air from the continent to the southern half of the U.K and Ireland from Tuesday onwards. This rain may hang around through to Thursday next week when things start to settle down again as a weak high pushes the low away. As usual that low pressure is slow moving so it may mean quite a heavy hit of rain for the south and Ireland if it manifests itself.

Agronomic Notes

This week I’m going to cover a topic that’s slightly contentious, that of overseeding…

If I had a pound (or a euro) for the times I’ve heard this response, I’d be a very rich man…”I overseed for sure, sometimes you can see a great take, but a few weeks later nothing” Usually the reason given is cutting height during the season, i.e you have to wait till we get good temperatures to aid speedy germination, but by then you’re at summer cutting height and that hinders seedling establishment. Whilst I’m sure this is a valid contributory factor, as are summer play levels,  I’m beginning to think they aren’t the main barriers to achieving effective establishment of seed.

Before we get into specifics, let’s just consider what we’re trying to achieve by overseeding ? Obviously we’re looking to add a new grass species / cultivar to an existing sward, but what is our objective ? To tick a box and say I’m overseeding to try and encourage ‘finer grasses’, blardy blah and thereby keep yourself or ‘the powers that be’ content ? …maybe….

Often we’re trying to introduce a different species / cultivar in an effort to make the overall sward ‘better’…but what is ‘better’ ?

In a golf green scenario, the objective is to give balance to the sward, reduce the homogenous nature of its composition and thereby impart ‘better’ sward characterstics…On a sportsfield or golf tee, the objective is often different, maybe better wear resistance and / or playability.

One of those key objectives in this day and age of ever-increasing legislation is better disease resistance….For example introducing bentgrass into a Poa sward will definitely give benefits in terms of reduced disease pressure from Fusarium, but before we look at how best to achieve this, shouldn’t we ask ourselves, why the bent isn’t there in the first place and why the current grass species (in this example Poa) is ?

Ultimately a grass sward will compromise a mixture of species, some more dominant than others, but it’s a natural situation which we manipulate un-naturally, both culturally (with cutting height, aeration, irrigation) and chemically (with PGR’s, fertiliser, etc). If we just overseed into an existing sward without changing the management practices I reckon it’s tantamount to p***ing in the wind, and will achieve little or nothing. First we have to understand why the existing sward comprises of the grass species that it does. Next we have to assess if its possible to change any or some of these factors to achieve a change in grass sward composition. We then have to change the ‘ground conditions’ before we introduce our chosen grass species.

I say ‘chosen grass species’ because at this point most of us will consult ‘the list’ of cultivars and assess which ones have ‘the best’ ratings, but that in itself isn’t really a guide as to whether this applies to your situation or not because every turf scenario is different. The geographical location, fertility regime, pH, PGR usage, organic matter levels, etc on the trial ground will be every bit as individual as your golf greens or sports pitches and the chances that the two are similar are remote in my way of thinking….So just because it says in a list that one cultivar is ‘better’ than another, it doesn’t mean that that difference will necessarily transfer itself to your situation. I saw some bentgrass plots recently sown down last autumn and if you look at the brochure and trials ratings vs. the reality in the plots, the two couldn’t be more dissimilar.

So where am I going with this discussion ?, well trialing cultivars in your scenario is the only way of truly seeing if one is better suited to it or not than the other…obviously this isn’t straight-forward, but it is worth it rather than just going through the motions..

The biggest barrier to effective overseeding in my humble opinion (but not the only one) is surface organic matter, I hesitate to say thatch because most people will say “I haven’t got thatch on my turf surfaces”, taking thatch to mean excessive organic matter. Surface organic matter doesn’t have to be excessive in depth (> 12mm say) to be an effective barrier to overseeding. If it is not adequately integrated with topdressing then even if it’s only 8mm, there’s no way that the seed will get beyond the seedling stage.

bridged

I don’t think I’ll overseed this year then…..

The easiest way to see if your surface is suitable to overseeding into is to take a plug, say 40mm deep and run a knife up the plug until you reach the bottom of the fibre layer. Lightly compress this between your thumb and forefinger and measure it. Then try and pull the surface fibre apart and look at the rooting characteristic. If it takes alot of effort to pull apart, chances are that the surface fibre isn’t adequately integrated with topdressing and furthermore, the roots will be bridged sideways because they physically can’t develop a root through the surface fibre layer.

So ask yourself, if the existing, established grass species has a rooting characterstic like this, what chance for a new seedling to develop it’s first adventitious roots  through the surface fibre layer ? Little or none I’d say and maybe that’s why sometimes you see that initial ‘take’ of seed and then it disappears, because it cannot develop a good enough root system to support a growing seedling and so ‘checks out’, over-run by plants that have adapted to the conditions better. (Usually Poa on a golf green)

So the best overseeding practice has to rely on overcoming this impediment aOverseedingnd increasingly I think this is hollow coring or solid tining because it removes (one way or another) the physical barrier to establishment. I saw this graphically illustrated last week (see image right) on a number of courses, not only does it provide a perfect environment for the new seed to develop in, but it also shelters it below the canopy and more importantly, the cutting height. With more vigorous species, like Ryegrass, I’m sure that slit seeding using machines like the Vredo can achieve the same result, but with Fescue or Bentgrass, I remain to be convinced that this is as effective a solution.

I mentioned changing management practices earlier and of course one of these is PGR usage (that old Cheshnut I hear you say) because once you’ve started down the road of introducing new seedlings into a sward, it doesn’t make sense to try and retard their growth with a growth regulator, so there’s a compromise that needs to be made if and when you embark down this road. This is of course dependent on the species you’re introducing, if it’s Ryegrass then it is less-affected by TE usage and so applying once it reaches the two-leaf stage appears fine, but is this the same for Fescue or Bentgrass ?,I think not because they are affected more by the use of TE. You could argue that TE affects the existing Poa more than the newly-established seedlings of Fescue and Bent, but I’d like to see some work on this that proves it. Certainly using TE before overseeding is a proven management tool because you reduce the competitive advantage of the existing sward components prior to overseeding.

Food for thought I hope, sorry for the late posting of this blog this week…

All the best
Mark Hunt