Seed rot and seedling diseases are a threat to peanut plants in every field.
Peanut seed must be protected from a number of fungal pathogens to reduce the threat of seed rot. One of the most common seed-rot fungal pathogens is Rhizopus, though there are others as well. If not effectively managed, the rotted seed in a now soft and putrid form will fail to germinate.
Poor quality seed is at increased risk to both rot and seedling disease. Damaged or poor-quality seed is more likely infected with fungal pathogens than would be “healthy seed”; low vigor from poor quality seed will also put the compromised seedlings at further risk to stand loss. Young plants need to be protected from fungal pathogens, primarily Aspergillus niger and Rhizoctonia solani.
Environment has a HUGE impact on risk to seed rots and seedling diseases. Planting into cool and wet soils increases risk to rots in general and to seedling disease caused by Rhizoctonia solani. Planting into hot and dry conditions greatly increases risk to Aspergillus crown rot. To reduce risk to these diseases, growers are encouraged to consider environmental conditions at planting and to delay planting if conditions now in the next week favor disease. Growers can reduce threat to these diseases by avoiding planting into cool soils or by using irrigation, if available, to cool hot and dry soils.
Fungicide seed treatments (preferably Rancona or Trebuset) are a first and critical line of defense to minimize impact of seed rots and seedling diseases. In 2023, some seed will have been treated with a liquid polymer rather than the dry dust that has been used seemingly since time began. The polymer has a blue-green color; though the color is different the efficacy is stout and unchanged.
Where there is elevated risk to seedling diseases, perhaps because of concerns over seed quality, or conditions at planting, growers may consider use of an in-furrow product to protect young plants against seedling disease and later against Cylindrocladium black rot (CBR) and perhaps white mold.
in-furrow products, to include azoxystrobin, Velum, Propulse, and Proline can be used to protect the crop from disease. Note: Just because a grower CAN use an in-furrow product does not mean a grower will make more money by doing so. Care must be taken in the decision process.
Azoxystrobin: 6 fl oz/A to 12 fl oz/A (3-6 fl oz/A under twin rows): very effective against Rhizoctonia seedling disease, much less effective now against Aspergillus crown rot disease.
Velum: used primarily as a nematicide at a rate of 6.5-6.84 fl oz/A (3.4 fl oz/A under twin rows), Velum also has outstanding activity against Aspergillus crown rot if this is needed. Use of velum also helps growers with a good start to early season control of leaf spot diseases, even though it is applied in the furrow. NOTE: Because of the cost, I do not believe that in the absence of peanut root-knot nematodes, most growers will benefit from use of Velum if it is ONLY applied for control of seedling diseases.
Proline: used in-furrow primarily if there is concern for management of CBR or, perhaps, early season white mold control. 5.7 fl oz/A under single rows, 2.85 fl oz/A under twin rows.
Use of Proline in-furrow is our best option for management of Cylindrocladium black rot (CBR) and Proline applied in-furrow may have some benefit for management of early season white mold as well. An in-furrow application of Proline is not as effective as a banded application of Proline 3 to 5 weeks after planting; but it should have some efficacy.
Propulse: this product is a pre-mix of fluopyram (Velum) and prothioconazole (Proline) and is used at a rate of 13.6 fl oz/A (single rows) and 6.8 fl oz/A (twin rows). Propulse would be used for reasons similar to Velum or Proline. Note: it is necessary to spike Propulse, 13.6 fl oz/A with 1 fl oz/A of Velum to have equivalent rates in an application. Again, growers should consider carefully what they are trying to manage with use of Propulse in-furrow at planting time on peanuts.
Nematicides are an important consideration for growers who have a problem with the peanut root-knot nematode by who do not plant TifNV-HiOL or Georgia-14N. Fumigation with Telone II (4.5-6 gal/A) 10-14 days prior to planting is our most effective nematode management option. However, growers can also successfully manage nematodes with AgLogic 15G (7 lb/A) and with Velum. (6.5-6.84 fl oz/A). Vydate CLV (34 fl oz/A) has also proven to be effective in the management of root-knot nematodes on peanut. But these critical management options must be deployed before the furrow is closed.
Final note: Use of AgLogic and Vydate at labeled rates provide effective control of thrips but to not aide in management of Tomato spotted wilt disease.
Use of azoxystrobin, Velum, Proline, or Propulse requires additional management of thrips, likely with Thimet or imidacloprid.
Only Thimet effectively reduces risk to Tomato spotted wilt.