Signum WG Fungicide: Target Diseases, Registered Crops and Application Timing
An advisor's guide to Signum WG (boscalid + pyraclostrobin) in Turkey: registered crops, target diseases, application timing, resistance management and PHI.
· BKÜ GPT Team · Signum WG, boscalid, pyraclostrobin, fungicide, grey mould, powdery mildew, blossom blight, BASF, Turkey
Signum WG is a broad-spectrum fungicide registered in Turkey, containing 26.7% boscalid + 6.7% pyraclostrobin. Marketed by BASF Türk Kimya under registration no. 5032 dated 24 February 2005, it is an imported water-dispersible granule (WG). What makes Signum WG interesting for an advisor is that it combines two distinct modes of action in one product and carries 16 registered uses, spanning vegetables, stone fruit, turf and ornamentals. This guide walks through Signum WG usage the way it comes up in a recommendation workflow: which disease, which crop, which timing, and which resistance constraints.
What is BKÜ GPT?
BKÜ GPT is a free application that lists plant protection products registered in Turkey (BKÜ — Bitki Koruma Ürünleri) by crop, disease, active ingredient or trade name, and answers questions in a chat interface. It covered 5,597 registered products at last count, growing as new products are registered. The product data in this article comes from the app's Signum WG label page.
Which diseases is Signum WG used against?
The registered target list of Signum WG covers most of the disease groups an advisor prescribes for in vegetable and fruit production:
- Grey mould (Botrytis cinerea) — on greenhouse tomato, pepper, aubergine and strawberry.
- Powdery mildew — on field and greenhouse tomato (Leveillula taurica) and carrot (Erysiphe heraclei, Leveillula taurica).
- Blossom blight (Monilinia laxa) — on peach, cherry and apricot.
- White mould (Sclerotinia sclerotiorum) — on lettuce and greenhouse cucumber.
- Alternaria leaf blights — early blight on potato (Alternaria solani), Alternaria cucumerina on watermelon.
- Onion rust (Puccinia porri) — on onion.
- Soil-borne diseases — Fusarium and Rhizoctonia on turf, damping-off (Rhizoctonia spp.) on greenhouse carnation.
The practical consequence: if one holding has grey mould in greenhouse tomato and a Botrytis problem in the strawberry plot next door, Signum WG can enter the programme as a single product registered for both. That convenience has to be weighed against the resistance constraint described below.
Which crops is Signum WG registered on?
Registered crop, target disease, dose and pre-harvest interval (PHI):
| Crop | Disease | Dose | PHI |
|---|---|---|---|
| Tomato (field) | Powdery mildew (Leveillula taurica) | 100 g/da | 3 days |
| Tomato (greenhouse) | Powdery mildew, grey mould (Botrytis cinerea) | 60 g / 100 L water | 3 days |
| Pepper (greenhouse) | Grey mould | 150 g / 100 L water | 3 days |
| Aubergine (greenhouse) | Grey mould | 150 g / 100 L water | 3 days |
| Cucumber (greenhouse) | White mould (Sclerotinia sclerotiorum) | 150 g / 100 L water | 3 days |
| Strawberry | Grey mould | 150 g / 100 L water | 3 days |
| Potato | Early blight (Alternaria solani) | 100 g/da | 3 days |
| Watermelon | Alternaria leaf blight (Alternaria cucumerina) | 100 g/da | 3 days |
| Carrot | Powdery mildew | 150 g/da | 1 day |
| Lettuce | White mould | 150 g/da | 7 days |
| Onion | Onion rust (Puccinia porri) | 150 g/da | 7 days |
| Peach | Blossom blight (Monilinia laxa) | 75 g / 100 L water | 7 days |
| Cherry | Blossom blight | 75 g / 100 L water | 7 days |
| Apricot | Blossom blight | 100 g / 100 L water | 7 days |
| Carnation (greenhouse) | Damping-off (Rhizoctonia spp.) | 150 g / 100 L water | — |
| Turf | Soil-borne diseases (Fusarium, Rhizoctonia) | 150 g/da | — |
Two details deserve attention. On greenhouse tomato the dose is 60 g per 100 L, while the other greenhouse vegetables take 150 g; mixing those up when prescribing the same product across a greenhouse is a common mistake. Second, the 75–100 g / 100 L range on stone fruit varies by crop. Because registration records get updated, it is worth checking the current Signum WG crop and dose table before writing a recommendation. To compare the other registered options on tomato and strawberry, use the tomato products and strawberry products pages.
When should Signum WG be applied?
The boscalid–pyraclostrobin pair is protectant with some early curative activity; both actives stop spore germination and germ-tube elongation. Signum WG therefore performs best when applied once infection conditions are present but before symptoms spread:
- Grey mould: periods of high humidity at 15–20 °C, overcast days with limited greenhouse ventilation, and the post-pruning or post-harvest windows when leaf wounds increase.
- Blossom blight on stone fruit: the application has to coincide with flowering; a spray after petal fall catches the infection too late.
- Powdery mildew: at the first white spots, or before spots appear where regional disease pressure is known.
Add the water-dispersible granule to the tank with the agitator running and use the spray mix the same day. If a tank mix with other products is planned, run a small-scale compatibility test first.
Active ingredients: how do boscalid and pyraclostrobin work?
Boscalid is a succinate dehydrogenase inhibitor (SDHI) with translaminar and acropetal movement within the leaf; it blocks Complex II of the fungal respiratory chain. Pyraclostrobin is a strobilurin (QoI) targeting Complex III, with protectant and curative properties. Attacking two different points of the respiratory chain gives a more reliable effect and a wider disease spectrum than a strobilurin used alone.
On toxicity, both actives show low mammalian toxicity (acute oral LD50 in rats > 5000 mg/kg). However, pyraclostrobin is highly toxic to fish; drift and runoff into watercourses, drainage channels and ponds must be prevented. It is classed as slightly toxic to bees, but for flowering-time stone fruit applications in orchards with hives, move the spray to the evening.
Signum WG resistance management: FRAC 7 + FRAC 11
This is the product's main constraint. SDHI (FRAC 7) and QoI (FRAC 11) are both classed as high-resistance-risk groups, and resistance to both has been reported worldwide in Botrytis cinerea and powdery mildew pathogens. Combining the two actives reduces the risk but does not remove it. Principles for a recommendation programme:
- Do not exceed the label's seasonal application limit, and avoid back-to-back applications.
- The application following Signum WG should come from a group other than FRAC 7 or FRAC 11; multi-site protectants (FRAC M) fit the rotation well.
- If another SDHI (e.g. fluopyram, fluxapyroxad) or another strobilurin (azoxystrobin, trifloxystrobin) has been used in the same season, those count towards the same group limit as Signum WG.
- Cultural measures — greenhouse ventilation, removal of infected plant debris, balanced nitrogen — reduce chemical pressure and slow resistance selection.
Summary for advisors
With its two-mode-of-action spectrum and short pre-harvest intervals across vegetables and fruit, Signum WG is a strong protectant tool in greenhouse and orchard programmes. Preserving its value means preventive timing, label dose, the crop-specific PHI and rotation with non-FRAC 7/11 products. For the current registration status, the full crop–disease–dose table and equivalent products with the same actives, see the Signum WG page on BKÜ GPT.
Frequently asked questions
Which diseases is Signum WG used against? Grey mould (Botrytis cinerea), powdery mildew, blossom blight (Monilinia laxa), white mould (Sclerotinia sclerotiorum), Alternaria leaf blights, onion rust and soil-borne Rhizoctonia/Fusarium diseases.
What is the Signum WG dose on tomato? 100 g/da against powdery mildew on field tomato; 60 g per 100 L of water against powdery mildew and grey mould on greenhouse tomato. PHI is 3 days for both. Verify the current label before use.
What is the pre-harvest interval of Signum WG? 1–7 days by crop: 1 day on carrot; 3 days on tomato, pepper, aubergine, cucumber, strawberry, potato and watermelon; 7 days on lettuce, onion, peach, cherry and apricot.
What are the active ingredients of Signum WG? 26.7% boscalid (FRAC 7, SDHI) and 6.7% pyraclostrobin (FRAC 11, QoI), as a BASF water-dispersible granule (WG).
Does Signum WG carry a resistance risk? Yes. Both SDHI and QoI are high-resistance-risk groups. Apply preventively, stay within the label's seasonal limit and rotate with fungicides from other mode-of-action groups.
BKÜ GPT is for information only. Verify every dose, pre-harvest interval and registration detail in this article against the current product label before issuing a recommendation. Growers should follow their licensed agronomist's instructions before applying any pesticide.