Recently by Philip Vickers

Alas, the rains have started as the hose pipe ban begins! The weather forecast will be closely monitored over the coming weeks, as this will dictate the direction of forth-coming fungicide programs.

At present wheat crops have generally had a modest amount of PGR (trinexapac-ethyl + chlormequat) in with a T0, with the view of following on with a further PGR application at T1.  With the many farmers applying more nitrogen early (in fear of a drought), the second PGR application may have to be robust.

Forward wheats are approaching growth stage 32, so T1 fungicides will begin within 7 days. Generally second wheat programs will be based on a prothioconazole or boscalid product, with chlorothalonil or strob added where appropriate. High potential wheat crops may receive an SDHI at T1, particularly if the weather increases disease pressure. Whatever happens, the Oakley will be sprayed every 3-4 weeks as it is a particularly susceptible variety to rust.

This season is a complete contrast to last season as far as my cereal crops are concerned. Wheat crops are between growth stages 12 and 31. The later crops are presently being treated with a low dose of trinexapac-ethyl to encourage rooting. 

Crops approaching GS 31 are receiving their first PGR, a robust programme is planned, and will be reviewed over the coming weeks. I am planning a T0 on all winter wheat crops. Product of choice will be a triazole, chlorothalonil mix, achieving at least one triazole unit.

The big talking point at the moment is Oakley, yellow rust is rampant in some crops. This variety will need careful monitoring and a robust rate of fungicide.

Winter arrived last week, with temperatures as low as -12C near Market Rasen (a colleague at Holbeach recorded -16C). Unlike last year, there was very little snow cover to protect the crops. 

The task of identifying light leaf spot in oilseed rape (OSR) crops will be challenging, as at first glance frost damage can appear similar.  OSR leaf samples will be heading to my airing cupboard for incubation.  This is unfortunate, as I have only just emptied the fridge of soil samples to be tested for soil mineral nitrogen. Who would marry an agronomist? 

HGCA topic sheet 75, 2003 states if 25% of plants are infected with light leaf spot an appropriate fungicide should be applied at the earliest opportunity.  With the current high value of OSR, and if the variety is susceptible to light leaf spot combined with the current cooler weather, I think we will be well rewarded for treating where infections are above 15%.

What happened to the promised October snow!

 

Since my last article we have still not had any significant rainfall (or snow!), just days of mist, and unseasonably warm temperatures.

 

The temperatures have encouraged rapid blackgrass growth, if the blackgrass has 2 or more leaves I am still encouraging autumn Atlantis use.  At the same time we have to be mindful that this product needs to go onto a dry leaf, and dry on.  Needless to say the spray window each day is not that long. Atlantis should be applied with a residual partner, my early results with prosulfocarb as a tank mix partner are looking favourable.

The dry weather continues. At the time of writing large parts of my area have received less than 25mm of rain this autumn. As such the seedbeds are still relatively open, and the residual herbicides used to date are unlikely to have created as good a chemical seal as last year.

That said, you can see blackgrass being affected by the residuals. The fact the blackgrass emergence has been delayed, combined with earlier drilling and fewer stale seedbeds could result in a challenging year on some farms.  

To help control the annual grass weeds this autumn, I am eager to use a contact chemical such as iodosulfuron-methyl-sodium or pyroxsulam. Both these products will need to be applied with a residual partner.

We have had a very smooth drilling period with little interference from the weather. I wish the same could be said about the chemical applications.

We seem to have had weeks of high winds. The fact that OSR broad-leaved weed sprays have been delayed may have compromised control - particular weeds that may cause concern are cranesbill and poppies. If these weeds are present I am considering the use of Bifenox, but this can only be applied under a Specific Off Label Application (SOLA). I hope the level of control will match last year's results. 

The moisture content of cereal seed-beds varies greatly, depending on location, soil type and cultivations. The present dry weather has reduced the effectiveness of stale seed-beds, with less blackgrass germinating now than in early-drilled rape crops. Failure to reduce blackgrass numbers pre-drilling will create challenges later in the year, so be prepared.

With harvest progressing well, and the new season rapidly approaching, now is a good time to look at the state of the soil in terms of nutrient content, pH and structure. Soil testing may be time consuming, but the rewards of getting the pH and nutrient status correct are immense. With the high price of potash and phosphate it is important to target applications against crop need. 

 

The increasing cost of diesel is an incentive to check the soil structure, sub-soiling needs to be targeted to the fields that have soil structure problems, and the depth at which the legs are pulled needs careful consideration. Digging a soil pit is the only way to determine how deep the soil needs cultivating.

 

Where blackgrass is a problem, the cultivations used need to be based around a blackgrass control strategy. With little seed returned to the soil this year there is a need to avoid bringing previous seasons seeds to the surface. Stale seed-beds provide a cost-effective method of reducing blackgrass populations.

Spring beans will be receiving a final bruchid spray as they finish flowering. A pyrethroid and half rate pirimicarb will be used as levels of black bean aphids are increasing. This will be our third bruchid spray in some cases due to the protracted season. Disease levels are still low in bean crops so a low rate triazole and chlorothalonil will be sufficient to keep the crop clean.

The early-maturing oilseed rape varieties are nearing desiccation timing. After recent rains picked up some late nitrogen it has, thankfully, prolonged the pod filling period. All crops will be treated with glyphosate (unless they are for seed).

Most of these treatments will include a pod sealant. With the current value of the seed we are trying to reduce the risk of pod shatter and ensure we harvest as much of the seed yield as we can.

At last the rain has arrived, 20mm in the last 10 days. Wheat crops are between growth stage 47 (flag leaf sheath opening) and growth stage 69 (flowering complete). 

My thoughts are focused on the HGCA guide, guidelines to minimise risk the of fusarium mycotoxins in cereals.  Each field will need to assessed individually, depending on the variety, weather, growth stage and the timing of the last fungicide. 

If a treatment is required then I will base it on prothioconazole, metconazole or tebuconazole. Depending on previous treatments and crop potential a strobe may be included.  I feel we also need to keep a close eye on mildew levels, after the rain one week ago levels of mildew on stressed crops have increased rapidly.

With the recent rains, the risk of damage from orange wheat blossom midge on susceptible varieties will increase. But treatments will only be made if thresholds are reached.