May updates from Teagasc for the Nursery Stock and Ornamental plant industry.
Teagasc Flower trials tour June 11-12, pest and disease updates: powdery mildew downy mildew, botrytis, diamondback moth, Rimpro charts, Xylella - no change following review
Teagasc Advisory - Nursery Stock & Ornamentals Newsletter May 2019
Sales have remained strong in the last month for most growers. The shortage of specific species of stock remains a challenge for growers and landscapers but will see prices at least staying steady.
The interest in bee friendly plants and planting schemes continues to grow. World bee day was held on May 20th. Even the European Commission was promoting that its banned the outdoor use of neonics.
Bloom running for the 13th year continued this trend with pollinators and biodiversity being very stong themes in the show gardens.
Anthony Ryan Landscapes, Kieran Dunne and Kildare Growers developed another Gold medal winning garden for Crumlin Childrens Hospital.
Tóg go bóg é was designed and built by students of Cabra College, showing strong use of native plants including distinctive Irish heather.
Teagasc, Nursery Stock Study tour to NetherlandsFlower trials 11th-12th June.
Each year the main pot plant, bedding and ornamental plant breeders of Netherlands open to visitors for four days. Its a popular event with many irish prouyers visiting to meet suppliers and find new innovative plants. Teagasc have organised a short tourof so of the key sites. The tour is open to anyone in the trade or students who would like to see latest in ornamental plant breeding. See details of the visit and costs here.
Pest, disease and plant protection product updates.
Keep up-to-date with the latest pesticides new by visiting the Teagasc pesticide blog.
Dr Michael Gaffney, Teagasc Entomologist has reported the start of the seasonal influx of Diamond Back Moth (DBM). "Diamond Back Moths have now arrived at our monitoring plots in Ashtown and Kinsealy in North Dublin. This migration seems to be coming from Scandinavia, through the UK (reports of sightings in Lincolnshire late last week). While the numbers observed seem low, the continued good weather this week may see an increase in population. It would be advisable for all brassica growers to check crops and take appropriate control measures. Monitoring these moths is relatively easy, as they move quickly up off the foliage when disturbed by people walking through the crop. They can be identified by the white markings on their back (picture below), thought to be diamond in shape". The source of the pest population is important as some are resistant to pyrethroids e.g. Deltamethrin and Lambda Cyhalothrin. Good alternative would include Bacillus thuringiensis or Indoxocarb. There are a small number of ornamental plants that are attacked by DBM; these include Aubretia, stock and wallflowers.
You can see the latest Teagasc Pest updates for weeks 17 & 18 here
Woolly Aphid
Reports are coming in again of woolly aphids on beech - aswell as some late frost damage. Natural predators that control aphids and help to check population levels include: Earwigs, ladybirds and the parasitic wasp Aphelinus mali.
Best practice for control:
Good coverage is essential; higher volume sprays are likely to give best results. Use of an appropriate wetter should help.
High volume sprays of fatty acids maltodextrin (Majestic) are least harmful to the environment and may suit public sites/ stud farms etc. Most effective at low levels of infestation. (Note not approved for apples)
Pesticides must penetrate past the waxy fluff over the colony, to be effective.
Suggestions of ‘pre-treatment’ of Epsom Salts (magnesium sulphate) at 12kg-15kg/ha to soften the waxiness, applied some 48 hours ahead of the scheduled insecticide.
Neonic Tepeki (Flonicamid) is specifically recommended for control of woolly aphid on apple and pear. Gazelle (Acetamiprid) is selective and less harmful to natural predators. Calypso (Thiachloprid) is another neonic. Some restrictions are in place for these chemicals and each plant and on or off label use should be checked.
Batavia (Spirotetramat) controls a wide range of sucking pests – its systemic so should be very effective, be mindful of scorch with it though.
FRAC group 3 Synthetic pyrethroids etc are broad spectrum and have a have a short persistence e.g. Decis,
Pymetrozine (Plenum) is very selective and useful (not approved for apples)
FastPro and RimPro modles predict scab and powdery mildew in apple trees. The information is very useful to ornamental Malus growers also. Contact me if you would like to get regular email updates.
Mildew & Botrytis
With cool temperatures and low light conditions forecast to persist for the next week, conditions will be ideal for Downy mildew to develop in the field and botrytis under protection. Powdery Mildew has been seen already during warmer weeks in May.
Downy Mildew
This disease favours cool and humid conditions; wet leaves in poorly ventilated areas are ideal for it to take hold. It will be familiar to you if you leave basil plants in a plastic sleeve for too long. Its recognised by white/grey felting on the underside of the leaf, the top of the leaf can show signs; yellowing or purple and eventually death of the leaf section. Hosts of various species of downy mildew include; Coleus, Impatiens, Alysum, Digitalis, Verbena, Veronica, Geranium, Argyranthemum. etc. Prevention is by eliminating the favourable conditions; increase ventilation, reduce water on leaves to a minimum, good hygiene and house keeping to remove sources of inoculum. Control options begin with prevention rather than curing the disease. There is no one size fits all, what works well for one strain of the mildew may not work well for another. Options include: Revus 40, Bumper 3, Dithane M3, Ridomil gold 4+M3, Signum 7+11, Mirage* 3, Orius P* 3 +3, Barclay Eyetak* 3. There are no established biocontrol options.
Powdery Mildew
There are a number of different species of fungi that cause powdery mildew however they all favour warm, dry weather and require humid conditions initially to establish. Teagasc use a disease modelling programme, RimPro (see above), for top fruit and it has been predicating high disease pressure from powdery mildew in previous weeks.
Powdery mildew can be recognised by white or off-white fungal growth usually on the upper surface of leaves but can also be found on stems, flowers and lower leaf surfaces. It affects a wide range of plants including; Acer, Aster, Crataegus, Salvia, Spirea, Phlox, Quercus, Roses, and Prunus. Perennials include Aster, Monarda, geranium, Phlox, Salvia, Verbena etc.
Prevention- good growing conditions that reduce humidity, adequate plant spacing and ventilation in glasshouse/polytunnels, will help to prevent powdery mildew developing. AQ 10 a biopesticide may be useful as a protectant especially in protected environments. In soft fruit production silicone via fertigation systems has been seen to reduce susceptibility of strawberries to Podospharea aphanis. Some sulphur products are available as preventative fungicides. Control - where Mildew is present in a crop some knock down will be required. Potassium bicarbonate (e.g. K50) is useful in protected environments. SB Plant Invigorator is well established in use and is labelled for the control of Powdery mildew. Good coverage is essential, a wetter such as Silwet should help.
The fungicide options below are eradicant and protectant, however not all fungicides control all species of powdery mildew. Use of a range of actives is advised unless you are certain of the species of mildew.:
Systhane/Bumper 3
Signum 7+11
Switch 9+12
Boogie Xpro 7+3+5
Fielder SE M5 + 12
Cello 3+5+3
Vareon 3 +3+ 12
Flexity/Vivando U8
On roses an additional product Stroby 11 is available for use as a protectant.
Growers should rotate mode of action (numbers above) to prevent resistance developing. Spray programmes can be as close together as every 7 days depending on disease pressure, weather conditions and product. Always follow the label instructions.
Botrytis
This disease also known as grey mould prospers in cool, humid conditions, not dissimilar to those suited to downy mildew. The very obvious fluffy grey brown is seen on stems, leaves fruit and flowers. Ajuga, Paeonia and Primula are amongst many plants that are host to the disease. Control of climate and hygiene are the best routes to prevent Botrytis. The disease easily enters plants via damaged points e.g after pruning or taking cuttings. Excellent air circulation, removal of dead leaves/fruit and good hygiene will help to reduce the development of botrytis.
Biological control is well established using the likes of Serenade and Prestop.
Chemical control options: Amistar 11, Bravo 500* M5, Signum 7+11, Switch 9+12, Electis M3 +22. Outdoor conditions would allow some products containing Trifloxystrobin which has been shown to be very effective. IR4 in USA has completed a good efficacy summary of Botrytis control products (pdf)
Xylella updates
A risk review of the impact of Xylella in Europe was published recently by the EFSA. It summarises the large amount of research completed in the last 3 years. In brief there is little major change of the actions being taken to control the spread of the bacteria - there is no cure available and the "cordon sanitaire" remains the advised strategy where it is found. "EFSA’s Plant Health Panel (PLH) used computer modelling to simulate how Xylella fastidiosa spreads across short and long distances under different conditions. The modelling showed the importance of implementing the control measures specified by the European Commission to prevent further spread and even eradicate outbreaks". There is good news however. A revised analysis of the climatic suitability of Xylella to the European climate suggests that most of Ireland is at low risk of the bacteria establishing here. Full details here:
Reminder - Products with use up dates in 2019 and 2020
There are significant changes in the products which can be used this year. Below is a selection of the main products used on farm which have a use up date in 2019. The full list is here.
Recommendations
1. Products with a use up date in 2019
The following is a list of the main products which have a use up by date in 2019.
Products with use up date in 2020
A number of commonly used products should be used up in the 2019 season due to the active ingredient being subject to EU regulation and will be withdrawn from the market.
Most of these products cannot be used in 2020
Teagasc, Nursery Stock Study tour to Germany and visit to Baumschule Technik Tradeshow 27th -30th August.
Four day study tour to the centre of German Nursery Stock production. Includes seven nursery visits and attending the world famous trade show. There is enormous variety in Pinneberg district with a high degree of specialization. World famous nurseries in the area include Kordes young plants and roses, Lorenz von Ehren,
Direct flights available from Dublin to Hamburg. See here for proposed itinerary and costs.
Please get in touch if you would like further information, if you have any issues you would like to discuss or topics you would like to hear more about. Feel free to forward the bulletin to friends or suppliers; they can subscribe or view past bulletins from the Teagasc web site. Please seek permission before reproduction of any part of the bulletin.
*All recommendations are made in good faith. As plant protection products recommendations can change please read the product label fully and check the PCS web site. The Teagasc nursery stock bulletin is now on the approved list for IASIS continuous professional development points. Subscribers will receive 5 CPE points per annum.
