Purple amaranth ( Amaranthus blitum L. ) , also known as livid amaranth , was identify for the first meter in March 2019 in an decorative greenhouse specimen planted in soilless sensitive sent into Michigan State University Plant & Pest Diagnostics for other psychoanalysis . In August 2019 , it was again identified in samples from a couple of veg growing systems in the southwest portion of Michigan . Since that time , it was take in in two other greenhouse locating again in soilless media .
Figure 1 . Purple amaranth seedling . Photo by Erin Hill , MSU .
There are no previous record of this species in the herbarium for the res publica of Michigan ; however , it has been obtain in several other states , peculiarly along the East Coast and in the South , agree to the USDA Plants Database . Though it is unreadable how this species came to Michigan , it appears establish on the level of the infestations in the vegetable theater and multiple nursery sighting , that it has been here for a couple of year or maybe more .
Figure 2 . purplish amaranth ( right ) has deep notch compared to other common Amaranthus hypochondriacus specie like Powell amaranth ( left ) . Photo by Erin Hill , MSU .
While no new weed metal money are welcome , the most concerning thing about this mintage is that one of the theater of operations - collected population has been tested and found to be repellent to Groups 5 and 7 weed killer , i.e. , photosystem II ( PSII ) inhibitors , such as prometryn and linuron , thus set options for commercial grower . trial run are ongoing to square up the level of resistance to these two land site of action .
Figure 3 . Purple amaranth ( right ) has a extremely branched outgrowth habit compare to other Chenopodium album like Powell amaranth ( remaining ) , which generally have one fundamental bow . pic by Ben Werling , MSU Extension .
Not all populations found in Michigan are resistive ; a second field - population from a different part of the land was not repellent . Previous report of herbicide electric resistance in this species were note between 1978 - 1993 in New Jersey ( Group 2 , Camellia State - resistant ) , France ( Group 5 , PSII - resistant ) , Switzerland ( Group 5 , PSII - resistant ) and Malaysia ( Group 22 , photosystem I - resistive ) , according to Heap 2020 .
Figure 4 . The seeds of purplish amaranth are small bootleg and glossy , about the size of a pinhead , and house in a capsule , which makes them floaty and easily seen on the filth surface . Photo by Erin Hill , MSU .
There are several features of imperial amaranth that put it apart from our top native lamb’s-quarters ( Powell amaranth , redroot lamb’s-quarter and liquid pigweed ) and even from our glyphosate - insubordinate pigweed invaders ( Palmer amaranth and vulgar waterhemp ) . The folio tips of imperial amaranth are all deep notch ( Figs . 1 and 2 ) . This species is also highly branched unlike the other pigweeds mentioned , which typically have one central theme ( Fig . 3 ) .
Figure 5 . Many seeds of empurpled amaranth can be seen in their abridgment on the soil airfoil . pic by Ben Werling , MSU Extension . Though it come out to be highly prolific ( i.e. , produces a luck of seed ) like the other pigweed species , these purple amaranth seeds are more freely unblock from the flora and stay within the capsule ( papery covering ) ( Figs . 4 and 5 ) , according to Costea et al . 2003 . semen are produced on every plant ( monecious , unlike Palmer amaranth and common waterhemp ) at the ends of offshoot and in leaf axils with an coming into court thinner than that of the native wild spinach ( Fig . 6 ) .
Figure 6 . Inflorescences of Powell amaranth ( leave ) and purplish amaranth ( right ) . Photo by Ben Werling , MSU Extension .
Sushila Chaudhari , MSU Department of Horticulture ’s unexampled comestible forte crops weed scientist , will be investigate the distribution of this locoweed mintage in Michigan as well as the biology and ascendency choice uncommitted . If you have see purple amaranth in your field or greenhouse , please feel devoid to contact Chaudhari ( [ electronic mail protected ] ) , Ben Werling ( [ email protected ] ) or Erin Hill ( [ email protect ] ) with more information .
generator : Michigan State University ( Erin Hill , Sushila Chaudhari and Benjamin Werling )
