This is a prohibition (negative command), which can be expressed by ne (or another negative word) + perfect subjunctive. Here the negative word is nullam.
Allen & Greenough sec. 450; see note 4:
- Prohibition is regularly expressed in classic prose (1) by nōlī with the Infinitive, (2) by cavē with the Present Subjunctive, or > (3) by nē with the Perfect Subjunctive:
(1) “ nōlī putāre” (Lig. 33) , do not suppose (be unwilling to suppose).
“ nōlī impudēns esse ” (Fam. 12.30.1) , don’t be shameless.
“ nōlīte cōgere sociōs ” (Verr. 2.1.82) , do not compel the allies.
(2) cavē “putēs” (Att. 7.20) , don’t suppose (take care lest you suppose).
“ cavē īgnōscās ” (Lig. 14) , do not pardon.
“ cavē festīnēs ” (Fam. 16.12.6) , do not be in haste.
(3) “ nē necesse habueris” (Att. 16.2.5) , do not regard it as necessary.
“ nē sīs admīrātus ” (Fam. 7.18.3) , do not be surprised.
“hōc facitō; hōc nē fēceris ” (Div. 2.127) , thou shalt do this, thou shalt not do that.
“ nē Apellae quidem dīxeris ” (Fam. 7.25.2) , do not tell Apella even.
“ nē vōs quidem mortem timueritis ” (Tusc. 1.98) , nor must you fear death.
All three of these constructions are well established in classic prose. The first, which is the most ceremonious, occurs oftenest; the third, though not discourteous, is usually less formal and more peremptory than the others.
Note 4.–> Other negatives sometimes take the place of nē > :—
“ nihil īgnōveris ” (Mur. 65) , grant no pardon (pardon nothing).
“ nec mihi illud dīxeris ” (Fin. 1.25) , and do not say this to me.
http://www.perseus.tufts.edu/hopper/text?doc=AG+450&fromdoc=Perseus%3Atext%3A1999.04.0001
seueris is from sero – to sow or plant
"Don’t plant any other tree before (you plant) the sacred vine . . "
Another ode – maybe the most famous of all, and in the same meter (“Greater Asclepiadean”) – begins with the ne + perfect subjunctive construction (1.11):
Tu ne quaesieris–scire nefas–quem mihi, quem tibi
finem di dederint, Leuconoe . . .
“Don’t you ask–it’s not right to know–what ending the gods have given me, have given you, Leuconoe . . .”
Leuconoe is apparently consulting Babylonios numeros, i.e., astrology.
The last line includes two words even people who know no Latin know:
. . . dum loquimur fugerit inuida
aetas. carpe diem, quam minimum credula postero.
“. . . even while we’re talking, jealous time will have fled. Pluck the day, putting as little faith as possible in the next one.”